A combination of Multiple-Input Multiple-Output Spatial Division Multiplexing technology and Orthogonal Frequency Division Multiplexing technique, namely MIMO-OFDM systems, been well-known as a potential technology to provide high speed data transmission and spectrum efficiency to attain throughput of 1 Gbit/sec and beyond improves link reliability for modern wireless communications. The rising development of Internet related contents and demand of multimedia services leads to increasing curiosity to high speed communications. It has been shown that by using MIMO system, it is possible to increase that capacity considerably.
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 Novel Alamouti STBC Technique for MIMO System Using 16- QAM Modulation and ...IJERA Editor
The wireless communication is the emerging field of research among communication researchers and they are
continuously working towards the reduction if error occurred in the signal during transmission through wireless
media. In this paper the wireless system is simulated with the application of Alamouti space time block codes
(STBC) with MIMO and MISO configurations to compare the results. The modulation technique used here is
16-QAM which is giving better results than other counterparts and to enhance the performance of the system i.e.
to reduce the effect of errors on data we have applied a moving average filter(MAF). The performance of the
system is shown with the simulation results with variable data sizes and found that the proposed approach is
better for the system.
Iterative qr decompostion channel estimation for mimo ofdm systems eSAT Journals
Abstract Channel estimation algorithms have a key role in signal detection in MIMO-OFDM systems. In this system, the number of channel components which need to be estimated is much more than conventional SISO wireless systems. Consequently, the computational process of channel estimation is highly intensive. In addition, the high performance channel estimation algorithms mostly suffer from high computational complexity. In the other words, the system undergoes intensive computations if high performance efficiency is desired. However, there is an alternative solution to achieve both high performance efficiency and relatively low level of computational complexity. In this solution, high efficient channel estimation is firstly designed, and then it is simplified using alternative mathematical expressions. In this paper, Iterative channel estimation based on QR decomposition for MIMO-OFDM systems is proposed. From simulation results, the iterative QRD channel estimation algorithm can provide better mean-square-error and bit error rate performance than conventional methods. Index Terms: MIMO, OFDM, QRD,Least squre Channel estimation
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 Novel Alamouti STBC Technique for MIMO System Using 16- QAM Modulation and ...IJERA Editor
The wireless communication is the emerging field of research among communication researchers and they are
continuously working towards the reduction if error occurred in the signal during transmission through wireless
media. In this paper the wireless system is simulated with the application of Alamouti space time block codes
(STBC) with MIMO and MISO configurations to compare the results. The modulation technique used here is
16-QAM which is giving better results than other counterparts and to enhance the performance of the system i.e.
to reduce the effect of errors on data we have applied a moving average filter(MAF). The performance of the
system is shown with the simulation results with variable data sizes and found that the proposed approach is
better for the system.
Iterative qr decompostion channel estimation for mimo ofdm systems eSAT Journals
Abstract Channel estimation algorithms have a key role in signal detection in MIMO-OFDM systems. In this system, the number of channel components which need to be estimated is much more than conventional SISO wireless systems. Consequently, the computational process of channel estimation is highly intensive. In addition, the high performance channel estimation algorithms mostly suffer from high computational complexity. In the other words, the system undergoes intensive computations if high performance efficiency is desired. However, there is an alternative solution to achieve both high performance efficiency and relatively low level of computational complexity. In this solution, high efficient channel estimation is firstly designed, and then it is simplified using alternative mathematical expressions. In this paper, Iterative channel estimation based on QR decomposition for MIMO-OFDM systems is proposed. From simulation results, the iterative QRD channel estimation algorithm can provide better mean-square-error and bit error rate performance than conventional methods. Index Terms: MIMO, OFDM, QRD,Least squre Channel estimation
VLSI Implementation of OFDM Transceiver for 802.11n systemsIJERA Editor
Orthogonal Frequency Division Multiplexing (OFDM) is the most widely used modulation technique for wireless communication network. In this paper, 4 x 4 spatially multiplexed MIMO OFDM transceiver is designed using 1/2 encoder and 64 bit FFT. The implementation has been carried out in hardware using Field Programmable Gate Array (FPGA). Both the transmitter and the receiver are implemented on a single FPGA board with the channel being a wired one. The FPGA board used is Diligent Atlys Xilinx Spartan 6. We have analysed the effect of Bit Error Rate and Data rate with respect to Signal to Noise ratio.
MIMO radar is introduced in presentation ,its advantage .future scope,research area.
MIMO radars represent a new generation of radars. In contrast to the traditional phased-array radar in which the transmit elements can transmit only the scaled versions of same signal, a MIMO radar allows the transmitters to transmit multiple signals. This waveform diversity offers enhanced flexibility in transmit beampattern synthesis which is an important area of MIMO radar signal processing
Performance Analysis of OSTBC MIMO Using Precoder with ZF & MMSE EqualizerIJERA Editor
In this paper, a bit error rate analysis is presented for multiple-input–multiple-output (MIMO) system with finite-bit feedback is considered in PSK modulation technique, where a transmit signal consists of a rotational precoder followed by an orthogonal space–time block code (OSTBC) which achieve full diversity when a linear receiver, such as, zeroforcing (ZF) or minimum mean square (MMSE), is used. By choosing different parameters, codes with different symbol rates and orthogonally can be obtained .In this paper, we compare the performance of a family of space-time codes. Simulations show how the precoders obtained by our proposed criterion and method perform better bit error rate reduction compared to the existing ones.
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.
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.
Ber analysis of 2x2 mimo spatial multiplexing under awgn and rician channels ...ijwmn
Multiple-input–multiple-output (MIMO) wireless systems use multiple antennas at transmitting and
receiving end to offer improved capacity and data rate over single antenna systems in multipath channels.
In this paper we have investigated the Spatial Multiplexing technique of MIMO systems. Here different
fading channels like AWGN and Rician are used for analysis purpose. Moreover we analyzed the technique
using high level modulations (i.e. M-PSK for different values of M). Detection algorithms used are Zero-
Forcing and Minimum mean square estimator. Performance is analyzed in terms of BER (bit error rate) vs.
SNR (signal to noise ratio).
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.
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
MIMO Channel Estimation Using the LS and MMSE AlgorithmIOSRJECE
Wireless Communication Technology has developed over the past few yearsfor other objectives.The Multiple InputMultiple Output (MIMO) is one of techniques that is used to enhancethe data rates, in which multiple antennas are employed both the transmitter and receiver. Multiple signals are transmitted from different antennas at the transmitter using the same frequency and separated space. Various channel estimation techniques are employed in order to judge the physical effects of the medium present. In this paper, we analyze and implementvarious estimation techniques for MIMO Systems such as Least Squares (LS), Minimum Mean Square Error (MMSE),these techniques are therefore compared to effectively estimate the channel in MIMO System. The results demonstrate that SNR required to support different values of bit error rate varies depending on different low correlation between the transmitting and the receiving antennas .In addition, it is illustrated that when the number of transmitter and receiver antennas increases, the performance of TBCE schemes significantly improves. The Same behavior isalso observed for MIMO system. Performance of both MMSE and LSestimation are the same for allkinds of modulation at small value of SNR but the more we increase the SNR value the more performance gap goes on increasing.
Bit Error Rate Performance of MIMO Spatial Multiplexing with MPSK Modulation ...ijsrd.com
Wireless communication is one of the most effective areas of technology development of our time. Wireless communications today covers a very wide array of applications. In this, we study the performance of general MIMO system, the general V-BLAST architecture with MPSK Modulation in Rayleigh fading channels. Based on bit error rate, we show the performance of the 2x2 schemes with MPSK Modulation in noisy environment. We also show the bit error rate performance of 2x2, 3x3, 4x4 systems with BPSK modulation. We see that the bit error rate performance of 2x2 systems with QPSK modulation gives us the best performance among other schemes analysed here.
VLSI Implementation of OFDM Transceiver for 802.11n systemsIJERA Editor
Orthogonal Frequency Division Multiplexing (OFDM) is the most widely used modulation technique for wireless communication network. In this paper, 4 x 4 spatially multiplexed MIMO OFDM transceiver is designed using 1/2 encoder and 64 bit FFT. The implementation has been carried out in hardware using Field Programmable Gate Array (FPGA). Both the transmitter and the receiver are implemented on a single FPGA board with the channel being a wired one. The FPGA board used is Diligent Atlys Xilinx Spartan 6. We have analysed the effect of Bit Error Rate and Data rate with respect to Signal to Noise ratio.
MIMO radar is introduced in presentation ,its advantage .future scope,research area.
MIMO radars represent a new generation of radars. In contrast to the traditional phased-array radar in which the transmit elements can transmit only the scaled versions of same signal, a MIMO radar allows the transmitters to transmit multiple signals. This waveform diversity offers enhanced flexibility in transmit beampattern synthesis which is an important area of MIMO radar signal processing
Performance Analysis of OSTBC MIMO Using Precoder with ZF & MMSE EqualizerIJERA Editor
In this paper, a bit error rate analysis is presented for multiple-input–multiple-output (MIMO) system with finite-bit feedback is considered in PSK modulation technique, where a transmit signal consists of a rotational precoder followed by an orthogonal space–time block code (OSTBC) which achieve full diversity when a linear receiver, such as, zeroforcing (ZF) or minimum mean square (MMSE), is used. By choosing different parameters, codes with different symbol rates and orthogonally can be obtained .In this paper, we compare the performance of a family of space-time codes. Simulations show how the precoders obtained by our proposed criterion and method perform better bit error rate reduction compared to the existing ones.
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.
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.
Ber analysis of 2x2 mimo spatial multiplexing under awgn and rician channels ...ijwmn
Multiple-input–multiple-output (MIMO) wireless systems use multiple antennas at transmitting and
receiving end to offer improved capacity and data rate over single antenna systems in multipath channels.
In this paper we have investigated the Spatial Multiplexing technique of MIMO systems. Here different
fading channels like AWGN and Rician are used for analysis purpose. Moreover we analyzed the technique
using high level modulations (i.e. M-PSK for different values of M). Detection algorithms used are Zero-
Forcing and Minimum mean square estimator. Performance is analyzed in terms of BER (bit error rate) vs.
SNR (signal to noise ratio).
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.
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
MIMO Channel Estimation Using the LS and MMSE AlgorithmIOSRJECE
Wireless Communication Technology has developed over the past few yearsfor other objectives.The Multiple InputMultiple Output (MIMO) is one of techniques that is used to enhancethe data rates, in which multiple antennas are employed both the transmitter and receiver. Multiple signals are transmitted from different antennas at the transmitter using the same frequency and separated space. Various channel estimation techniques are employed in order to judge the physical effects of the medium present. In this paper, we analyze and implementvarious estimation techniques for MIMO Systems such as Least Squares (LS), Minimum Mean Square Error (MMSE),these techniques are therefore compared to effectively estimate the channel in MIMO System. The results demonstrate that SNR required to support different values of bit error rate varies depending on different low correlation between the transmitting and the receiving antennas .In addition, it is illustrated that when the number of transmitter and receiver antennas increases, the performance of TBCE schemes significantly improves. The Same behavior isalso observed for MIMO system. Performance of both MMSE and LSestimation are the same for allkinds of modulation at small value of SNR but the more we increase the SNR value the more performance gap goes on increasing.
Bit Error Rate Performance of MIMO Spatial Multiplexing with MPSK Modulation ...ijsrd.com
Wireless communication is one of the most effective areas of technology development of our time. Wireless communications today covers a very wide array of applications. In this, we study the performance of general MIMO system, the general V-BLAST architecture with MPSK Modulation in Rayleigh fading channels. Based on bit error rate, we show the performance of the 2x2 schemes with MPSK Modulation in noisy environment. We also show the bit error rate performance of 2x2, 3x3, 4x4 systems with BPSK modulation. We see that the bit error rate performance of 2x2 systems with QPSK modulation gives us the best performance among other schemes analysed here.
Grayscale Image Transmission over Rayleigh Fading Channel in a MIMO System Us...IJERA Editor
The consistent demand for higher data rates and ability to send large volumes of data without compromising the quality of communication has led the development of a new generations of wireless systems. But range and data rate limitations are there in wireless devices. In an effort to overcome these limitations, Multi Input Multi Output (MIMO) systems can be used which also increase diversity and improve the bit error rate (BER) performance of wireless systems. They also increase the channel capacity, increase the transmitted data rate through spatial multiplexing, and/or reduce interference from other users. MIMO systems thus make a promising communication systems because of their high transmission rates without additional bandwidth or transmit power and robustness against multipath fading. This paper focuses on transmission of an image file using 2x2 MIMO system that achieves a full diversity gain using Alamouti’s Space Time Block Coding technique for 2 transmitting antennas and 2 receiving antennas. Different modulation techniques viz. BPSK, QPSK, 16-QAM and 64-QAM are used and performances has been evaluated in terms of BER vs. SNR to find out the best modulation technique in a given environment. Space-Time Codes have been used which in addition to the time and spectral domain, also exploit the spatial domain. Simple maximum likelihood decoding algorithm is used at the receiver side to decode the received encoded signal.
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) .
Capacity Enhancement of MIMO-OFDM System in Rayleigh Fading ChannelIOSR Journals
Abstract: 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) . Keywords— Adaptive modulation ASTC code, Capacity, BER, Ergodic capacity, PAPR, Spectral Efficiency and SNR
In this paper, we analyzed a numerical evaluation of the performance of MIMO radio systems in the LTE network environment. Downlink physical layer of the OFDM-MIMO based radio interface is considered for system model and a theoretical analysis of the bit error rate of the two space-time codes (SFBC 2×1 and FSTD 4×2 codes are adopted by the LTE norm as a function of the signal to noise ratio. Analytical expressions are given for transmission over a Rayleigh channel without spatial correlation which is then compared with Monte-Carlo simulations. Further evaluated channel capacity and simulation results show throughput almost reaches to the capacity limit.
Multi user performance on mc cdma single relay cooperative system by distribu...IJCNCJournal
Increasing data rate and high performance is the target focus of wireless communication. The multi carrier on multi-hop communication system using relay's diversity technique which is supported by a reliable coding is a system that may give high performance. This research is developing a model of multi user and two scheme of multi carrier CDMA on multi hop communication system with diversity technique which is using Alamouti codes in Rayleigh fading channel. By Alamouti research, Space Time Block Code (STBC) for MIMO system can perform high quality signal at the receiver in the Rayleigh fading channel and the noisy system. In this research, MIMO by STBC is applied to single antenna system (Distributed-STBC/DSTBC) with multi carrier CDMA on multi hop wireless communication system (relay diversity) which is able to improve the received signal performance.
MC DS CDMA on multi hop wireless communication system with 2 hops is better performing than MC CDMA on multi user without Multi User Detector. To reach BER 10-3 multi hop system with MC CDMA needs more power 5 dB than MC DS CDMA at 5 users using Alamouti scheme for symbol transmission at the relay.
Intersymbol interference caused by multipath in band limited frequency selective time dispersive channels distorts the transmitted signal, causing bit error at receiver. ISI is the major obstacle to high speed data transmission over wireless channels. Channel estimation is a technique used to combat the intersymbol interference. The objective of this paper is to improve channel estimation accuracy in MIMO-OFDM system by using modified variable step size leaky Least Mean Square (MVSSLLMS) algorithm proposed for MIMO OFDM System. So we are going to analyze Bit Error Rate for different signal to noise ratio, also compare the proposed scheme with standard LMS channel estimation method.
Performance Enhancement in SU and MU MIMO-OFDM Technique for Wireless Communi...IJECEIAES
The consistent demand for higher data rates and need to send giant volumes of data while not compromising the quality of communication has led the development of a new generations of wireless systems. But range and data rate limitations are there in wireless devices. In an attempt to beat these limitations, Multi Input Multi Output (MIMO) systems will be used which also increase diversity and improve the bit error rate (BER) performance of wireless systems. They additionally increase the channel capacity, increase the transmitted data rate through spatial multiplexing, and/or reduce interference from other users. MIMO systems therefore create a promising communication system because of their high transmission rates without additional bandwidth or transmit power and robustness against multipath fading. This paper provides the overview of Multiuser MIMO system. A detailed review on how to increase performance of system and reduce the bit error rate (BER) in different fading environment e.g. Rayleigh fading, Rician fading, Nakagami fading, composite fading.
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.
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.
A New Transmission Scheme for MIMO – OFDMijsrd.com
This contribution introduces a new transmission scheme for multiple-input multiple-output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems. The new scheme is efficient and suitable especially for symmetric channels such as the link between two base stations or between two antennas on radio beam transmission. This survey Paper presents the performance analysis of V-BLAST based multiple inputs multiple output orthogonal frequency division multiplexing (MIMO-OFDM) system with respect to bit error rate per signal to noise ratio (BER/SNR) for various detection techniques. A 2X2 MIMO-OFDM system is used for the performance evaluation. The simulation results shows that the performance of V-BLAST based detection techniques is much better than the conventional methods. Alamouti Space Time Block Code (STBC) scheme is used with orthogonal designs over multiple antennas which showed simulated results are identical to expected theoretical results. With this technique both Bit Error Rate (BER) and maximum diversity gain are achieved by increasing number of antennas on either side. This scheme is efficient in all the applications where system capacity is limited by multipath fading.
Wireless communication now has been focus to increase data rate and high performance. The
multi carrier on multi-hop communication system using relay's diversity technique which is
supported by a reliable coding is a system that may give high performance.
This research is developing a model of multi carrier CDMA on multi hop communication
system with diversity technique which is using Alamouti codes in Rayleigh fading channel. By
Alamouti research, Space Time Block Code (STBC) for MIMO system can perform high quality
signal at the receiver in the Rayleigh fading channel and the noisy system. In this research,
MIMO by STBC is applied to single antenna system (Distributed-STBC/DSTBC) with multi
carrier CDMA on multi hop wireless communication system (relay diversity) which is able to
reduce the complexity of the system but the system performance even can be maintained and
improved.
MC CDMA on multi hop wireless communication system with 2 hops is performing much better
than Single Input Single Output (SISO) system (1 hop system). Power needed for 1 hop system to
have the same quality as 2 hops system to reach BER 10-3 is 12 dB. And multi hop system needs
orthogonal symbol to send from relay than original symbol to reach better performance. 12.5
dB power up is needed for multi hop system which sent same symbol as transmitter than relay
system which sent orthogonal symbol.
MC CDMA PERFORMANCE ON SINGLE RELAY COOPERATIVE SYSTEM BY DIVERSITY TECHNIQUE...cscpconf
Wireless communication now has been focus to increase data rate and high performance. The multi carrier on multi-hop communication system using relay's diversity technique which is
supported by a reliable coding is a system that may give high performance. This research is developing a model of multi carrier CDMA on multi hop communication system with diversity technique which is using Alamouti codes in Rayleigh fading channel. By Alamouti research, Space Time Block Code (STBC) for MIMO system can perform high quality signal at the receiver in the Rayleigh fading channel and the noisy system. In this research, MIMO by STBC is applied to single antenna system (Distributed-STBC/DSTBC) with multi carrier CDMA on multi hop wireless communication system (relay diversity) which is able to reduce the complexity of the system but the system performance even can be maintained andimproved.
MC CDMA on multi hop wireless communication system with 2 hops is performing much better than Single Input Single Output (SISO) system (1 hop system). Power needed for 1 hop system to have the same quality as 2 hops system to reach BER 10-3 is 12 dB. And multi hop system needs orthogonal symbol to send from relay than original symbol to reach better performance. 12.5 dB power up is needed for multi hop system which sent same symbol as transmitter than relay system which sent orthogonal symbol.
Computationally Efficient Multi-Antenna Techniques for Multi-User Two-Way Wire...IJECEIAES
In this work, we are interested in implementing, developing and evaluating multi-antenna techniques used for multi-user two-way wireless relay networks that provide a good tradeoff between the computational complexity and performance in terms of symbol error rate and achievable data rate. In particular, a variety of newly multi-antenna techniques is proposed and studied. Some techniques based on orthogonal projection enjoy low computational complexity. However, the performance penalty associated with them is high. Other techniques based on maximum likelihood strategy enjoy high performance, however, they suffer from very high computational complexity. The Other techniques based on randomization strategy provide a good trade-off between the computational complexity and performance where they enjoy low computational complexity with almost the same performance as compared to the techniques based on maximum likelihood strategy.
Similar to PERFORMANCE ANALYSIS OF CLIPPED STBC CODED MIMO OFDM SYSTEM (20)
Submission Deadline: 30th September 2022
Acceptance Notification: Within Three Days’ time period
Online Publication: Within 24 Hrs. time Period
Expected Date of Dispatch of Printed Journal: 5th October 2022
MODELING AND ANALYSIS OF SURFACE ROUGHNESS AND WHITE LATER THICKNESS IN WIRE-...IAEME Publication
White layer thickness (WLT) formed and surface roughness in wire electric discharge turning (WEDT) of tungsten carbide composite has been made to model through response surface methodology (RSM). A Taguchi’s standard Design of experiments involving five input variables with three levels has been employed to establish a mathematical model between input parameters and responses. Percentage of cobalt content, spindle speed, Pulse on-time, wire feed and pulse off-time were changed during the experimental tests based on the Taguchi’s orthogonal array L27 (3^13). Analysis of variance (ANOVA) revealed that the mathematical models obtained can adequately describe performance within the parameters of the factors considered. There was a good agreement between the experimental and predicted values in this study.
A STUDY ON THE REASONS FOR TRANSGENDER TO BECOME ENTREPRENEURSIAEME Publication
The study explores the reasons for a transgender to become entrepreneurs. In this study transgender entrepreneur was taken as independent variable and reasons to become as dependent variable. Data were collected through a structured questionnaire containing a five point Likert Scale. The study examined the data of 30 transgender entrepreneurs in Salem Municipal Corporation of Tamil Nadu State, India. Simple Random sampling technique was used. Garrett Ranking Technique (Percentile Position, Mean Scores) was used as the analysis for the present study to identify the top 13 stimulus factors for establishment of trans entrepreneurial venture. Economic advancement of a nation is governed upon the upshot of a resolute entrepreneurial doings. The conception of entrepreneurship has stretched and materialized to the socially deflated uncharted sections of transgender community. Presently transgenders have smashed their stereotypes and are making recent headlines of achievements in various fields of our Indian society. The trans-community is gradually being observed in a new light and has been trying to achieve prospective growth in entrepreneurship. The findings of the research revealed that the optimistic changes are taking place to change affirmative societal outlook of the transgender for entrepreneurial ventureship. It also laid emphasis on other transgenders to renovate their traditional living. The paper also highlights that legislators, supervisory body should endorse an impartial canons and reforms in Tamil Nadu Transgender Welfare Board Association.
BROAD UNEXPOSED SKILLS OF TRANSGENDER ENTREPRENEURSIAEME Publication
Since ages gender difference is always a debatable theme whether caused by nature, evolution or environment. The birth of a transgender is dreadful not only for the child but also for their parents. The pain of living in the wrong physique and treated as second class victimized citizen is outrageous and fully harboured with vicious baseless negative scruples. For so long, social exclusion had perpetuated inequality and deprivation experiencing ingrained malign stigma and besieged victims of crime or violence across their life spans. They are pushed into the murky way of life with a source of eternal disgust, bereft sexual potency and perennial fear. Although they are highly visible but very little is known about them. The common public needs to comprehend the ravaged arrogance on these insensitive souls and assist in integrating them into the mainstream by offering equal opportunity, treat with humanity and respect their dignity. Entrepreneurship in the current age is endorsing the gender fairness movement. Unstable careers and economic inadequacy had inclined one of the gender variant people called Transgender to become entrepreneurs. These tiny budding entrepreneurs resulted in economic transition by means of employment, free from the clutches of stereotype jobs, raised standard of living and handful of financial empowerment. Besides all these inhibitions, they were able to witness a platform for skill set development that ignited them to enter into entrepreneurial domain. This paper epitomizes skill sets involved in trans-entrepreneurs of Thoothukudi Municipal Corporation of Tamil Nadu State and is a groundbreaking determination to sightsee various skills incorporated and the impact on entrepreneurship.
DETERMINANTS AFFECTING THE USER'S INTENTION TO USE MOBILE BANKING APPLICATIONSIAEME Publication
The banking and financial services industries are experiencing increased technology penetration. Among them, the banking industry has made technological advancements to better serve the general populace. The economy focused on transforming the banking sector's system into a cashless, paperless, and faceless one. The researcher wants to evaluate the user's intention for utilising a mobile banking application. The study also examines the variables affecting the user's behaviour intention when selecting specific applications for financial transactions. The researcher employed a well-structured questionnaire and a descriptive study methodology to gather the respondents' primary data utilising the snowball sampling technique. The study includes variables like performance expectations, effort expectations, social impact, enabling circumstances, and perceived risk. Each of the aforementioned variables has a major impact on how users utilise mobile banking applications. The outcome will assist the service provider in comprehending the user's history with mobile banking applications.
ANALYSE THE USER PREDILECTION ON GPAY AND PHONEPE FOR DIGITAL TRANSACTIONSIAEME Publication
Technology upgradation in banking sector took the economy to view that payment mode towards online transactions using mobile applications. This system enabled connectivity between banks, Merchant and user in a convenient mode. there are various applications used for online transactions such as Google pay, Paytm, freecharge, mobikiwi, oxygen, phonepe and so on and it also includes mobile banking applications. The study aimed at evaluating the predilection of the user in adopting digital transaction. The study is descriptive in nature. The researcher used random sample techniques to collect the data. The findings reveal that mobile applications differ with the quality of service rendered by Gpay and Phonepe. The researcher suggest the Phonepe application should focus on implementing the application should be user friendly interface and Gpay on motivating the users to feel the importance of request for money and modes of payments in the application.
VOICE BASED ATM FOR VISUALLY IMPAIRED USING ARDUINOIAEME Publication
The prototype of a voice-based ATM for visually impaired using Arduino is to help people who are blind. This uses RFID cards which contain users fingerprint encrypted on it and interacts with the users through voice commands. ATM operates when sensor detects the presence of one person in the cabin. After scanning the RFID card, it will ask to select the mode like –normal or blind. User can select the respective mode through voice input, if blind mode is selected the balance check or cash withdraw can be done through voice input. Normal mode procedure is same as the existing ATM.
IMPACT OF EMOTIONAL INTELLIGENCE ON HUMAN RESOURCE MANAGEMENT PRACTICES AMONG...IAEME Publication
There is increasing acceptability of emotional intelligence as a major factor in personality assessment and effective human resource management. Emotional intelligence as the ability to build capacity, empathize, co-operate, motivate and develop others cannot be divorced from both effective performance and human resource management systems. The human person is crucial in defining organizational leadership and fortunes in terms of challenges and opportunities and walking across both multinational and bilateral relationships. The growing complexity of the business world requires a great deal of self-confidence, integrity, communication, conflict and diversity management to keep the global enterprise within the paths of productivity and sustainability. Using the exploratory research design and 255 participants the result of this original study indicates strong positive correlation between emotional intelligence and effective human resource management. The paper offers suggestions on further studies between emotional intelligence and human capital development and recommends for conflict management as an integral part of effective human resource management.
VISUALISING AGING PARENTS & THEIR CLOSE CARERS LIFE JOURNEY IN AGING ECONOMYIAEME Publication
Our life journey, in general, is closely defined by the way we understand the meaning of why we coexist and deal with its challenges. As we develop the "inspiration economy", we could say that nearly all of the challenges we have faced are opportunities that help us to discover the rest of our journey. In this note paper, we explore how being faced with the opportunity of being a close carer for an aging parent with dementia brought intangible discoveries that changed our insight of the meaning of the rest of our life journey.
A STUDY ON THE IMPACT OF ORGANIZATIONAL CULTURE ON THE EFFECTIVENESS OF PERFO...IAEME Publication
The main objective of this study is to analyze the impact of aspects of Organizational Culture on the Effectiveness of the Performance Management System (PMS) in the Health Care Organization at Thanjavur. Organizational Culture and PMS play a crucial role in present-day organizations in achieving their objectives. PMS needs employees’ cooperation to achieve its intended objectives. Employees' cooperation depends upon the organization’s culture. The present study uses exploratory research to examine the relationship between the Organization's culture and the Effectiveness of the Performance Management System. The study uses a Structured Questionnaire to collect the primary data. For this study, Thirty-six non-clinical employees were selected from twelve randomly selected Health Care organizations at Thanjavur. Thirty-two fully completed questionnaires were received.
Living in 21st century in itself reminds all of us the necessity of police and its administration. As more and more we are entering into the modern society and culture, the more we require the services of the so called ‘Khaki Worthy’ men i.e., the police personnel. Whether we talk of Indian police or the other nation’s police, they all have the same recognition as they have in India. But as already mentioned, their services and requirements are different after the like 26th November, 2008 incidents, where they without saving their own lives has sacrificed themselves without any hitch and without caring about their respective family members and wards. In other words, they are like our heroes and mentors who can guide us from the darkness of fear, militancy, corruption and other dark sides of life and so on. Now the question arises, if Gandhi would have been alive today, what would have been his reaction/opinion to the police and its functioning? Would he have some thing different in his mind now what he had been in his mind before the partition or would he be going to start some Satyagraha in the form of some improvement in the functioning of the police administration? Really these questions or rather night mares can come to any one’s mind, when there is too much confusion is prevailing in our minds, when there is too much corruption in the society and when the polices working is also in the questioning because of one or the other case throughout the India. It is matter of great concern that we have to thing over our administration and our practical approach because the police personals are also like us, they are part and parcel of our society and among one of us, so why we all are pin pointing towards them.
A STUDY ON TALENT MANAGEMENT AND ITS IMPACT ON EMPLOYEE RETENTION IN SELECTED...IAEME Publication
The goal of this study was to see how talent management affected employee retention in the selected IT organizations in Chennai. The fundamental issue was the difficulty to attract, hire, and retain talented personnel who perform well and the gap between supply and demand of talent acquisition and retaining them within the firms. The study's main goals were to determine the impact of talent management on employee retention in IT companies in Chennai, investigate talent management strategies that IT companies could use to improve talent acquisition, performance management, career planning and formulate retention strategies that the IT firms could use. The respondents were given a structured close-ended questionnaire with the 5 Point Likert Scale as part of the study's quantitative research design. The target population consisted of 289 IT professionals. The questionnaires were distributed and collected by the researcher directly. The Statistical Package for Social Sciences (SPSS) was used to collect and analyse the questionnaire responses. Hypotheses that were formulated for the various areas of the study were tested using a variety of statistical tests. The key findings of the study suggested that talent management had an impact on employee retention. The studies also found that there is a clear link between the implementation of talent management and retention measures. Management should provide enough training and development for employees, clarify job responsibilities, provide adequate remuneration packages, and recognise employees for exceptional performance.
ATTRITION IN THE IT INDUSTRY DURING COVID-19 PANDEMIC: LINKING EMOTIONAL INTE...IAEME Publication
Globally, Millions of dollars were spent by the organizations for employing skilled Information Technology (IT) professionals. It is costly to replace unskilled employees with IT professionals possessing technical skills and competencies that aid in interconnecting the business processes. The organization’s employment tactics were forced to alter by globalization along with technological innovations as they consistently diminish to remain lean, outsource to concentrate on core competencies along with restructuring/reallocate personnel to gather efficiency. As other jobs, organizations or professions have become reasonably more appropriate in a shifting employment landscape, the above alterations trigger both involuntary as well as voluntary turnover. The employee view on jobs is also afflicted by the COVID-19 pandemic along with the employee-driven labour market. So, having effective strategies is necessary to tackle the withdrawal rate of employees. By associating Emotional Intelligence (EI) along with Talent Management (TM) in the IT industry, the rise in attrition rate was analyzed in this study. Only 303 respondents were collected out of 350 participants to whom questionnaires were distributed. From the employees of IT organizations located in Bangalore (India), the data were congregated. A simple random sampling methodology was employed to congregate data as of the respondents. Generating the hypothesis along with testing is eventuated. The effect of EI and TM along with regression analysis between TM and EI was analyzed. The outcomes indicated that employee and Organizational Performance (OP) were elevated by effective EI along with TM.
INFLUENCE OF TALENT MANAGEMENT PRACTICES ON ORGANIZATIONAL PERFORMANCE A STUD...IAEME Publication
By implementing talent management strategy, organizations would have the option to retain their skilled professionals while additionally working on their overall performance. It is the course of appropriately utilizing the ideal individuals, setting them up for future top positions, exploring and dealing with their performance, and holding them back from leaving the organization. It is employee performance that determines the success of every organization. The firm quickly obtains an upper hand over its rivals in the event that its employees having particular skills that cannot be duplicated by the competitors. Thus, firms are centred on creating successful talent management practices and processes to deal with the unique human resources. Firms are additionally endeavouring to keep their top/key staff since on the off chance that they leave; the whole store of information leaves the firm's hands. The study's objective was to determine the impact of talent management on organizational performance among the selected IT organizations in Chennai. The study recommends that talent management limitedly affects performance. On the off chance that this talent is appropriately management and implemented properly, organizations might benefit as much as possible from their maintained assets to support development and productivity, both monetarily and non-monetarily.
A STUDY OF VARIOUS TYPES OF LOANS OF SELECTED PUBLIC AND PRIVATE SECTOR BANKS...IAEME Publication
Banking regulations act of India, 1949 defines banking as “acceptance of deposits for the purpose of lending or investment from the public, repayment on demand or otherwise and withdrawable through cheques, drafts order or otherwise”, the major participants of the Indian financial system are commercial banks, the financial institution encompassing term lending institutions. Investments institutions, specialized financial institution and the state level development banks, non banking financial companies (NBFC) and other market intermediaries such has the stock brokers and money lenders are among the oldest of the certain variants of NBFC and the oldest market participants. The asset quality of banks is one of the most important indicators of their financial health. The Indian banking sector has been facing severe problems of increasing Non- Performing Assets (NPAs). The NPAs growth directly and indirectly affects the quality of assets and profitability of banks. It also shows the efficiency of banks credit risk management and the recovery effectiveness. NPA do not generate any income, whereas, the bank is required to make provisions for such as assets that why is a double edge weapon. This paper outlines the concept of quality of bank loans of different types like Housing, Agriculture and MSME loans in state Haryana of selected public and private sector banks. This study is highlighting problems associated with the role of commercial bank in financing Small and Medium Scale Enterprises (SME). The overall objective of the research was to assess the effect of the financing provisions existing for the setting up and operations of MSMEs in the country and to generate recommendations for more robust financing mechanisms for successful operation of the MSMEs, in turn understanding the impact of MSME loans on financial institutions due to NPA. There are many research conducted on the topic of Non- Performing Assets (NPA) Management, concerning particular bank, comparative study of public and private banks etc. In this paper the researcher is considering the aggregate data of selected public sector and private sector banks and attempts to compare the NPA of Housing, Agriculture and MSME loans in state Haryana of public and private sector banks. The tools used in the study are average and Anova test and variance. The findings reveal that NPA is common problem for both public and private sector banks and is associated with all types of loans either that is housing loans, agriculture loans and loans to SMES. NPAs of both public and private sector banks show the increasing trend. In 2010-11 GNPA of public and private sector were at same level it was 2% but after 2010-11 it increased in many fold and at present there is GNPA in some more than 15%. It shows the dark area of Indian banking sector.
EXPERIMENTAL STUDY OF MECHANICAL AND TRIBOLOGICAL RELATION OF NYLON/BaSO4 POL...IAEME Publication
An experiment conducted in this study found that BaSO4 changed Nylon 6's mechanical properties. By changing the weight ratios, BaSO4 was used to make Nylon 6. This Researcher looked into how hard Nylon-6/BaSO4 composites are and how well they wear. Experiments were done based on Taguchi design L9. Nylon-6/BaSO4 composites can be tested for their hardness number using a Rockwell hardness testing apparatus. On Nylon/BaSO4, the wear behavior was measured by a wear monitor, pinon-disc friction by varying reinforcement, sliding speed, and sliding distance, and the microstructure of the crack surfaces was observed by SEM. This study provides significant contributions to ultimate strength by increasing BaSO4 content up to 16% in the composites, and sliding speed contributes 72.45% to the wear rate
ROLE OF SOCIAL ENTREPRENEURSHIP IN RURAL DEVELOPMENT OF INDIA - PROBLEMS AND ...IAEME Publication
The majority of the population in India lives in villages. The village is the back bone of the country. Village or rural industries play an important role in the national economy, particularly in the rural development. Developing the rural economy is one of the key indicators towards a country’s success. Whether it be the need to look after the welfare of the farmers or invest in rural infrastructure, Governments have to ensure that rural development isn’t compromised. The economic development of our country largely depends on the progress of rural areas and the standard of living of rural masses. Village or rural industries play an important role in the national economy, particularly in the rural development. Rural entrepreneurship is based on stimulating local entrepreneurial talent and the subsequent growth of indigenous enterprises. It recognizes opportunity in the rural areas and accelerates a unique blend of resources either inside or outside of agriculture. Rural entrepreneurship brings an economic value to the rural sector by creating new methods of production, new markets, new products and generate employment opportunities thereby ensuring continuous rural development. Social Entrepreneurship has the direct and primary objective of serving the society along with the earning profits. So, social entrepreneurship is different from the economic entrepreneurship as its basic objective is not to earn profits but for providing innovative solutions to meet the society needs which are not taken care by majority of the entrepreneurs as they are in the business for profit making as a sole objective. So, the Social Entrepreneurs have the huge growth potential particularly in the developing countries like India where we have huge societal disparities in terms of the financial positions of the population. Still 22 percent of the Indian population is below the poverty line and also there is disparity among the rural & urban population in terms of families living under BPL. 25.7 percent of the rural population & 13.7 percent of the urban population is under BPL which clearly shows the disparity of the poor people in the rural and urban areas. The need to develop social entrepreneurship in agriculture is dictated by a large number of social problems. Such problems include low living standards, unemployment, and social tension. The reasons that led to the emergence of the practice of social entrepreneurship are the above factors. The research problem lays upon disclosing the importance of role of social entrepreneurship in rural development of India. The paper the tendencies of social entrepreneurship in India, to present successful examples of such business for providing recommendations how to improve situation in rural areas in terms of social entrepreneurship development. Indian government has made some steps towards development of social enterprises, social entrepreneurship, and social in- novation, but a lot remains to be improved.
OPTIMAL RECONFIGURATION OF POWER DISTRIBUTION RADIAL NETWORK USING HYBRID MET...IAEME Publication
Distribution system is a critical link between the electric power distributor and the consumers. Most of the distribution networks commonly used by the electric utility is the radial distribution network. However in this type of network, it has technical issues such as enormous power losses which affect the quality of the supply. Nowadays, the introduction of Distributed Generation (DG) units in the system help improve and support the voltage profile of the network as well as the performance of the system components through power loss mitigation. In this study network reconfiguration was done using two meta-heuristic algorithms Particle Swarm Optimization and Gravitational Search Algorithm (PSO-GSA) to enhance power quality and voltage profile in the system when simultaneously applied with the DG units. Backward/Forward Sweep Method was used in the load flow analysis and simulated using the MATLAB program. Five cases were considered in the Reconfiguration based on the contribution of DG units. The proposed method was tested using IEEE 33 bus system. Based on the results, there was a voltage profile improvement in the system from 0.9038 p.u. to 0.9594 p.u.. The integration of DG in the network also reduced power losses from 210.98 kW to 69.3963 kW. Simulated results are drawn to show the performance of each case.
APPLICATION OF FRUGAL APPROACH FOR PRODUCTIVITY IMPROVEMENT - A CASE STUDY OF...IAEME Publication
Manufacturing industries have witnessed an outburst in productivity. For productivity improvement manufacturing industries are taking various initiatives by using lean tools and techniques. However, in different manufacturing industries, frugal approach is applied in product design and services as a tool for improvement. Frugal approach contributed to prove less is more and seems indirectly contributing to improve productivity. Hence, there is need to understand status of frugal approach application in manufacturing industries. All manufacturing industries are trying hard and putting continuous efforts for competitive existence. For productivity improvements, manufacturing industries are coming up with different effective and efficient solutions in manufacturing processes and operations. To overcome current challenges, manufacturing industries have started using frugal approach in product design and services. For this study, methodology adopted with both primary and secondary sources of data. For primary source interview and observation technique is used and for secondary source review has done based on available literatures in website, printed magazines, manual etc. An attempt has made for understanding application of frugal approach with the study of manufacturing industry project. Manufacturing industry selected for this project study is Mahindra and Mahindra Ltd. This paper will help researcher to find the connections between the two concepts productivity improvement and frugal approach. This paper will help to understand significance of frugal approach for productivity improvement in manufacturing industry. This will also help to understand current scenario of frugal approach in manufacturing industry. In manufacturing industries various process are involved to deliver the final product. In the process of converting input in to output through manufacturing process productivity plays very critical role. Hence this study will help to evolve status of frugal approach in productivity improvement programme. The notion of frugal can be viewed as an approach towards productivity improvement in manufacturing industries.
A MULTIPLE – CHANNEL QUEUING MODELS ON FUZZY ENVIRONMENTIAEME Publication
In this paper, we investigated a queuing model of fuzzy environment-based a multiple channel queuing model (M/M/C) ( /FCFS) and study its performance under realistic conditions. It applies a nonagonal fuzzy number to analyse the relevant performance of a multiple channel queuing model (M/M/C) ( /FCFS). Based on the sub interval average ranking method for nonagonal fuzzy number, we convert fuzzy number to crisp one. Numerical results reveal that the efficiency of this method. Intuitively, the fuzzy environment adapts well to a multiple channel queuing models (M/M/C) ( /FCFS) are very well.
Water billing management system project report.pdfKamal Acharya
Our project entitled “Water Billing Management System” aims is to generate Water bill with all the charges and penalty. Manual system that is employed is extremely laborious and quite inadequate. It only makes the process more difficult and hard.
The aim of our project is to develop a system that is meant to partially computerize the work performed in the Water Board like generating monthly Water bill, record of consuming unit of water, store record of the customer and previous unpaid record.
We used HTML/PHP as front end and MYSQL as back end for developing our project. HTML is primarily a visual design environment. We can create a android application by designing the form and that make up the user interface. Adding android application code to the form and the objects such as buttons and text boxes on them and adding any required support code in additional modular.
MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software. It is a stable ,reliable and the powerful solution with the advanced features and advantages which are as follows: Data Security.MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
Online aptitude test management system project report.pdfKamal Acharya
The purpose of on-line aptitude test system is to take online test in an efficient manner and no time wasting for checking the paper. The main objective of on-line aptitude test system is to efficiently evaluate the candidate thoroughly through a fully automated system that not only saves lot of time but also gives fast results. For students they give papers according to their convenience and time and there is no need of using extra thing like paper, pen etc. This can be used in educational institutions as well as in corporate world. Can be used anywhere any time as it is a web based application (user Location doesn’t matter). No restriction that examiner has to be present when the candidate takes the test.
Every time when lecturers/professors need to conduct examinations they have to sit down think about the questions and then create a whole new set of questions for each and every exam. In some cases the professor may want to give an open book online exam that is the student can take the exam any time anywhere, but the student might have to answer the questions in a limited time period. The professor may want to change the sequence of questions for every student. The problem that a student has is whenever a date for the exam is declared the student has to take it and there is no way he can take it at some other time. This project will create an interface for the examiner to create and store questions in a repository. It will also create an interface for the student to take examinations at his convenience and the questions and/or exams may be timed. Thereby creating an application which can be used by examiners and examinee’s simultaneously.
Examination System is very useful for Teachers/Professors. As in the teaching profession, you are responsible for writing question papers. In the conventional method, you write the question paper on paper, keep question papers separate from answers and all this information you have to keep in a locker to avoid unauthorized access. Using the Examination System you can create a question paper and everything will be written to a single exam file in encrypted format. You can set the General and Administrator password to avoid unauthorized access to your question paper. Every time you start the examination, the program shuffles all the questions and selects them randomly from the database, which reduces the chances of memorizing the questions.
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
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2. Performance Analysis of Clipped STBC Coded MIMO OFDM System
http://www.iaeme.com/IJECET/index.asp 29 editor@iaeme.com
1. INTRODUCTION
MIMO (Multiple Input, Multiple Output) is an antenna technology for wireless
communications in which multiple antennas are used at both the source (transmitter)
and the destination (receiver). The antennas at each end of the communications circuit
are combined to minimize errors and optimize data speed. MIMO is one of several
forms of smart antenna technology, the others being MISO (Multiple Input, Single
Output) and SIMO (Single Input, Multiple Output). In conventional wireless
communications, a single antenna is used at the source, and another single antenna is
used at the destination. In some cases, this gives rise to problems with multipath
effects. When an electromagnetic field (EM field) is met with obstructions such as
hills, canyons, buildings, and utility wires, the wave fronts are scattered, and thus they
take many paths to reach the destination. The late arrival of scattered portions of the
signal causes problems such as fading, cut-out (cliff effect), and intermittent reception
(picket fencing). In digital communications systems such as wireless Internet, it can
cause a reduction in data speed and an increase in the number of errors. The use of
two or more antennas, along with the transmission of multiple signals (one for each
antenna) at the source and the destination, eliminates the trouble caused by multipath
wave propagation, and can even take advantage of this effect.
MIMO technology has aroused interest because of its possible applications in
digital television (DTV), wireless local area networks (WLANs), metropolitan area
networks (MANs), and mobile communications.
2. MIMO SYSTEM
MIMO systems are composed of three main elements, namely the transmitter (TX),
the channel (H), and the receiver (RX). In NT is denoted as the number of antenna
elements at the transmitter, and Nr is denoted as the number of elements at the
receiver. It is important to note that the system is described in terms of the channel.
For example, the Multiple-Inputs are located at the output of the TX (the input to the
channel), and similarly, the Multiple-Outputs are located at the input of the RX (the
output of the channel).
The channel with Nr outputs and Nt inputs is denoted as a Nr X Nt matrix
where each entry hi;j denotes the attenuation and phase shift (transfer function)
between the jth
transmitter and the ith
receiver. It is assumed that the MIMO channel
behaves in a “quasi-static” fashion, i.e. the channel varies randomly between burst to
burst, but fixed within a transmission. This is a reasonable and commonly used
assumption as it represents an indoor channel where the time of change is constant
and negligible compared to the time of a burst of data. The MIMO signal model is
described as
r = Hs + n (1)
where, r is the received vector of size NR×1, H is the channel matrix of size NR ×NT ,
s is the transmitted vector of size NT×1, and n is the noise vector of size NR×1. Each
noise element is typically modelled as independent identically distributed (i.i.d.) white
Gaussian noise, with variance NT=2. An explanation for this model is as follows. The
3. Koiloth S R S Jyothsna and Tummala Aravinda Babu
http://www.iaeme.com/IJECET/index.asp 30 editor@iaeme.com
transmitted signals are mixed in the channel since they use the same carrier frequency.
At the receiver side, the received signal is composed of a linear combination of each
transmitted signal plus noise. The receiver can solve for the transmitted signals by
treating as a system of linear equations. If the channel H is correlated, the system of
linear equations will have more unknowns than equations. One reason correlation
between signals can occur is due to the spacing between antennas. To prevent
correlation due to the spacing, they are typically spaced at least c=2, where c is the
wavelength of the carrier frequency. The second reason correlation can occur is due to
lack of multipath components. It is for this reason that rich multipath is desirable in
MIMO systems. The multipath effect can be interpreted by each receive antenna
being in a different channel. For this reason, the rank of a MIMO channel is defined
as the number of independent equations offered. It is important to note that: rank (H)
< min (NR;NT) and therefore the maximum number of streams that a MIMO system
can support is upper-bounded by min(NR;NT). Since the performance of MIMO
systems depends highly on the channel matrix, it is important to model the channel
matrix realistically. The following section provides an overview of typical channel
models used for computer simulations.
3. SPACE–TIME BLOCK CODES (STBC)
Space–time block coding is a technique used in wireless communications to transmit
multiple copies of a data stream across a number of antennas and to exploit the
various received versions of the data to improve the reliability of data-transfer. The
fact that the transmitted signal must traverse a potentially difficult environment with
scattering, reflection, refraction and so on and may then be further corrupted by
thermal noise in the receiver means that some of the received copies of the data will
be 'better' than others.
Transmit antennas
Time slots
An STBC is usually represented by a matrix as shown above. Each row represents
a time slot and each column represents one antenna's transmissions over time. Here,
Sij is the modulated symbol to be transmitted in time slot i from antenna j. There are
to be T time slots and nT transmit antennas as well as nR receive antennas. This block
is usually considered to be of length T. The code rate of an STBC measures how
many symbols per time slot it transmits on average over the course of one block. If a
block encodes k symbols, the code-rate is r=k/T. Only one standard STBC can
achieve full-rate Alamouti's code. STBCs as originally introduced, and as usually
studied, are orthogonal. This means that the STBC is designed such that the vectors
representing any pair of columns taken from the coding matrix are orthogonal. The
result of this is simple, linear, optimal decoding at the receiver.
3.1 ALAMOUTI Space Time Block Code
Alamouti code is the first STBC that provides full diversity at full data rate for two
transmit antennas. Fig.1 shows the block diagram of the Alamouti space-time
encoder. S1= [ ,
4. Performance Analysis of Clipped STBC Coded MIMO OFDM System
http://www.iaeme.com/IJECET/index.asp 31 editor@iaeme.com
Figure 1 A block diagram of the Alamouti space-time encoder
The information bits are first modulated using an M-ary modulation scheme. The
encoder takes the block of two modulated symbols s1and s2 in each encoding
operation and hands it to the transmit antennas according to the code matrix
(2)
The first row represents the first transmission period and the second row the
second transmission period. During the first transmission, the symbols s1 and s2 are
transmitted simultaneously from antenna one and antenna two respectively. In the
second transmission period, the symbol is transmitted from antenna one and the
symbol from transmit antenna two. It is clear that the encoding is performed in
both time (two transmission intervals) and space domain (across two transmit
antennas). The two rows and columns of S are orthogonal to each other and the code
matrix is orthogonal
(3)
Where I2 is a (2 × 2) identity matrix. This property enables the receiver to detect s1 and
s2 by a simple linear signal processing operation. Let us look at the receiver side now.
Only one receive antenna is assumed to be available. The channel at time t may be
modelled by a complex multiplicative distortion h1(t) for transmit antenna one and
h2(t) for transmit antenna two as shown in equation 3.3 and 3.4. Assuming that the
fading is constant across two consecutive transmit periods of duration T, we can write
h1(t)= h1(t+T)=h1= (4)
h2(t)= h2(t+T)= h2= (5)
Where, |hi | and θi , i = 1, 2 are the amplitude gain and phase shift for the path from
transmit antenna i to the receive antenna. The received signals at the time t and t + T
can then be expressed as
= (6)
= (7)
Where, r1 and r2 are the received signals at time t and t + T, n1 and n2 are complex
random variables representing receiver noise and interference.
Information
source
Alamouti
Code S
Modulator
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3.2 Equivalent Virtual (2 × 2) Channel Matrix (EVCM) of the Alamouti
Code
Conjugating the signal r2 in that is received in the second symbol period, the received
signal may be written equivalently as r
= (8)
= (9)
Thus the equations 3.8 and 3.9 can be written as
= + (10)
or in short notation as
y = Hvs + (11)
Where, the modified receive vector y = [ ] T has been introduced. Hv will be
termed the Equivalent Virtual MIMO Channel Matrix (EVCM) of the Alamouti
STBC scheme. It is given by
Hv= (12)
Thus, by considering of the elements of y as originating from two virtual receive
antennas (instead of received samples at one antenna at two time slots) one could
interpret the (2 × 1) Alamouti STBC as a (2× 2) spatial multiplexing transmission
using one time slot. The key difference between the Alamouti scheme and a true (2 ×
2) multiplexing system lies in the specific structure of Hv. Unlike to a general i.i.d.
MIMO channel matrix, the rows and columns of the virtual channel matrix are
orthogonall.
= )I2 = I2 (13)
where I2 is the (2 × 2) identity matrix and h 2 is the power gain of the equivalent
MIMO channel with =( ). Due to this orthogonality the receiver of the
Alamouti scheme (discussed in detail in the following subsection) decouples the
MISO channel into two virtually independent channels each with channel gain h2
and
diversity d = 2. It is obvious that the EVCM depends on the structure of the code and
the channel coefficients. The concept of the EVCM simplifies the analysis of the
STBC transmission scheme. The existence of an EVCM is one of the important
characteristics of STBCs.
3.3 ASTBC Based MIMO OFDM System Model
Consider a space time block coded MIMO-OFDM system equipped with transmit
antennas and receive antennas as illustrated in Figure 2. The message bit sequence is
mapped into a sequence of BPSK symbols which will be converted into N parallel
symbol streams after serial to parallel conversion. Each of the N parallel symbol
streams is then encoded by the space-time block code encoder i=1,2,3.....NT
into where is the antenna index and is the symbol time index.
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Figure 2 Block Diagram of MIMO OFDM System using STBC coding.
The number of symbols in a space-time codeword is N=NT×NR. Then the symbol
streams are subjected to inverse fast Fourier transform operation followed by cyclic
prefix insertion between two consecutive OFDM symbols in order to reduce the effect
of the delay spread of the multipath channels. The length of the CP is adjustable and
must be set in order to keep a bandwidth efficient system without occurring inter
symbol interference or inter carrier interference. At the receiver, after removing the
CP and applying FFT, the transmitted symbol stream is estimated using the
received signal Assume the channel gain follows the Rayleigh distribution
from the ith
transmit antenna to jth
the receive antenna over the tth
symbol period. If the
channel gains do not change during T symbol periods, the symbol time index can be
omitted and as long as the transmit antennas and receive antennas are spaced
sufficiently apart, NT NR fading gain {hij} can be assumed to be statistically
independent. If is the transmitted signal from the ith
transmit antenna during tth
symbol period, the received signal at the jth
receive antenna during tth
symbol period is
given by
= (14)
where is the noise process at the jth
receive antenna during tth
symbol period, which
is modelled as the zero mean circular symmetric complex Gaussian (ZMCSCG) noise
of unit variance, and is the average energy of each transmitted signal.
In general we can write as
Y= (15)
3.3.1 BER Performance Evaluation
In order to make an investigation of performance analysis of the MIMO-OFDM
system with Alamouti Space Time Block Code as the transmit diversity and MRC
diversity technique as the receive diversity over a Rayleigh fading channel, we deal
with MATLAB simulation using the parameters based on IEEE802.a standard. BPSK
modulation was used to determine the BER versus SNR performance of the system.
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In digital transmission, the number of bit errors is the number of received bits of a
data stream over a communication channel that has been altered due to noise,
interference, distortion or bit synchronization errors. The bit error rate or bit error
ratio (BER) is the number of bit errors divided by the total number of transferred bits
during time interval.
In a noisy channel, the BER is often expressed as a function of the normalized
carrier-to-noise ratio measure denoted Eb/N0, (energy per bit to noise power spectral
density ratio), or Es/N0 (energy per modulation symbol to noise spectral density).
While in wireless communication, BER (dB) vs. SNR (dB) is used. The BER may be
analyzed using stochastic computer simulations.
3.4 Channel Capacity of MIMO OFDM System
It is the maximum amount of information that can reliably be transmitted over any
communication channel at any given instant. It is denoted by ‘C’ and can be given as
(16)
Where, B is Bandwidth in Hertz , S/N is Signal to Noise Ratio in watts or volts2
. For
MIMO the capacity is given by
(17)
Where, M is the minimum of MT (number of transmitting antennas) or MR (number of
receiving antennas).
3.4.1 Performance Analysis of MIMO OFDM System
The water filling algorithm has been employed to measure the performance of MIMO
OFDM integrated system.
3.4.1.1. Water Filling Algorithm
Water filling refers to a technique whereby the power for the spatial channels are
adjusted based on the channels gain. The channel with high gain and signal to noise
ratio gives more power. More power maximizes the sum of data rates in all sub
channels. The data rate in each sub channel is related to the power allocation by
Shannon’s G formula C = B log(1 + SNR). However, because of t is a logarithmic
function of power, the data rate is usually insensitive to the exact power allocation.
This motivates the search for simpler power allocation schemes that can perform close
to the optimal. The water filling algorithm is based on an iterative procedure. The
process of water filling algorithm is similar to pouring the water in the vessel .The
total amount on water filled (power allocated) is proportional to the Signal to Noise
Ratio of channel.
Power allocated by individual channel is given by
(19)
Where Pt is the power budget of MIMO system which is allocated among the different
channels and H is the channel matrix of system. The capacity of a MIMO is the
algebraic sum of the capacities of all channels and given by
(20)
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We have to maximize the total number of bits to be transported .As per the
scheme following steps are followed to carry out the water filling algorithm.
Algorithm Steps:-
1. Take the inverse of the channel gains.
2. Water filling has non uniform step structure due to the inverse of the Channel
gain.
3. Initially take the sum of the total power Pt and the inverse of the channel gain.
It gives the complete area in the water filling and inverse power gain
(21)
4. Decide the initial water level by the formula given below by taking the average
Power allocated
(22)
5. The power values of each subchannel are calculated by subtracting the inverse
Channel gain of each channel
(23)
In case the power allocated value become negative stop iteration.
3.5 Peak to Average Power Ratio (PAPR) in OFDM
The PAPR is the relation between the maximum power of a sample in a given OFDM
transmit symbol divided by the average power of that OFDM symbol. PAPR occurs
when in a multicarrier system the different sub-carriers are out of phase with each
other. At each instant they are different with respect to each other at different phase
values. When all the points achieve the maximum value simultaneously; this will
cause the output envelope to suddenly shoot up which causes a 'peak' in the output
envelope. Due to presence of large number of independently modulated subcarriers in
an OFDM system, the peak value of the system can be very high as compared to the
average of the whole system. This ratio of the peak to average power value is termed
as Peak-to- Average Power Ratio. For the discrete-time version x[n],PAPR is
expressed as
(24)
Where E[ ] is the expectation operator. PAPR is evaluated per OFDM symbol. An
OFDM signal consists of a number of independently modulated sub-carriers which
can give a large PAPR when added up coherently. When N signals are added with the
same phase they produce a peak power that is N times the average power of the
signal. So OFDM signal has a very large PAPR, which is very sensitive to
nonlinearity of the high power amplifier.
The performance of a PAPR reduction scheme is usually demonstrated by three
main factors: the Complementary Cumulative Distributive Function (CCDF), Bit
Error Rate (BER), and transmitted signal power. These factors are explained below
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3.5.1. Complementary Cumulative Distributive Function (CCDF)
In practice, the empirical CCDF is the most informative metric used for evaluating the
PAPR. PAPR reduction capability is measured by the amount of CCDF reduction
achieved. CCDF provides an indication of the probability of the OFDM signal’s
envelope exceeding a specified PAPR threshold within the OFDM symbol and is
given by
CCDF[ PAPR(xn
(t))] =prob(PAPR(xn
(t)> )) (25)
Where PAPR (xn
(t)) is the PAPR of the nth
OFDM symbol and is some threshold.
Based on the CLT, the envelope of the OFDM signal follows the Rayleigh
distribution and consequently its energy distribution becomes an exponential, or
equivalently, a central chi-square distribution with two degrees of freedom and zero
mean with a CDF given by
CDF( )=(1- ) (26)
The probability that the PAPR of the OFDM signal with N subcarriers is below a
threshold is the probability that all the N samples are below the threshold. Assuming
that the OFDM samples are mutually independent, this probability can be given as
prob(PAPR< )= CDF[ PAPR(xn
(t))] = (27)
3.5.2. Bit Error Rate
The performance of a modulation technique can be quantified in terms of the required
signal to noise ratio(SNR) to achieve a specific bit error rate (BER). Although the
main focus of PAPR reduction techniques is to reduce the CCDF, this is usually
achieved at the expense of increasing the BER. Clipping the high peaks of the OFDM
signal by the PA causes a substantial in-band distortion that leads to higher BER.
Other techniques may require that side information be transmitted as well. If the side
information is received incorrectly at the receiver, the whole OFDM symbol is
recovered in error and the BER performance degrades.
3.5.3. Transmitted signal power
Some PAPR reduction techniques require that the average power of the transmitted
signal be increased. If the linear region of the PA is not stretched to accommodate the
new signal, the signal will traverse the nonlinear region leading to higher distortions
and degraded BER performance. However, this solution increases the hardware cost.
3.6 PAPR Reduction Techniques
PAPR reduction techniques vary according to the requirement of the system and are
dependent on various factors such as PAPR Spectral efficiency, reduction capacity,
increase in transmit signal power, loss in data rate, complexity of computation and
increase in the bit-error rate(BER) at the receiver end are various factors which are
taken into account before adopting a PAPR reduction technique of the system.
3.6.1 PAPR Reduction by Clipping
One of the simplest signal distortion methods is the method of clipping the high peaks
of the OFDM signal prior to passing it through the PA. This method employs a clipper
that limits the signal envelope to a predetermined clipping level (CL) if the signal
exceeds that level; otherwise, the clipper passes the signal without change as defined
by
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(29)
where x[n] is the OFDM signal, CL is the clipping level and x[n] is the angle of x[n].
Clipping is a nonlinear process that leads to both in-band and out-of-band distortions.
While the latter one causes spectral spreading and can be eliminated by filtering the
signal after clipping, the former can degrade the BER performance and cannot be
reduced by filtering. However, oversampling by taking longer IFFT can reduce the in-
band distortion effect as portion of the noise is reshaped outside of the signal band
that can be removed later by filtering. Filtering the clipped OFDM signal can preserve
the spectral efficiency by eliminating the out-of band distortion and, hence, improving
the BER performance but it can lead to peak power re growth.
The simulations are conducted for the OFDM signal without clipping and when
clipping is used with a clipping ratio (CR) of 1dB and 5dB. The CR is related to the
clipping level by the expression
(30)
Where, E[x[n]] is the average of the OFDM signal x[n].
4 BER PERFORMANCE OF MIMO OFDM SYSTEM
At first the performance of Alamouti’s Space Time Block Coded MIMO-OFDM
system under Rayleigh fading channel is investigated with various antennas
configurations. The simulation model employs BPSK modulation scheme and
Alamouti’s coding scheme using two transmit antennas and more than one receive
antennas. Table 1 shows the OFDM parameters considered for simulation.
Table 1 OFDM parameters considered for simulation
Parameters Value
Modulation BPSK
FFT size 64
No of symbols 10^4
No of sub carriers 52
Figure 3 BER performance of ASTBC based MIMO OFDM system for various antenna
configurations
0 5 10 15 20 25
10
-5
10
-4
10
-3
10
-2
10
-1
SNR dB
BitErrorRate
BER Performance of Alamouti’s STBC for Various Antenna Configuration
Alamouti STBC (NT=2, NR=1)
Alamouti STBC (NT=2, NR=2)
Alamouti STBC (NT=2, NR=3)
Alamouti STBC (NT=2, NR=4)
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4.1. BER Performance with and without clipping
The simulations are conducted for the OFDM signal without clipping and when
clipping is used with a clipping ratio (CR) of 1dB and 5dB. The CR is related to the
clipping level by the expression. Figure below shows the BER performance of the
system with and without clipping and Empirical CCDF with and without clipping for
different values of CR.
Figure 4 BER performance with and without clipping for different values of CR
Figure 5 Empirical CCDF with and without clipping for different CR
Table 2 shows the parameters used for simulation of clipping technique.
Table 2 Parameters used for simulation of clipping technique
Parameters Value
Modulation BPSK
FFT size 64
No of symbols 10^4
No of sub carriers 52
Clipping Ratio 1dB,5Db
4.2 Deterministic Channel Capacity of MIMO-OFDM System
For a MIMO system with NT transmits and NR receive antennas, a narrowband time-
invariant wireless channel can be represented by NR NT deterministic matrix
H . Consider a transmitted symbol vector x which is composed of NT
0 2 4 6 8 10 12 14 16 18 20
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
SNR(dB)
BER
BER without clipping and with clipping for different values of CR
no clipping
CR = 5dB
CR = 1dB
0 2 4 6 8 10 12
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
PAPR threshold(dB)
CCDF
Empirical CCDF without clipping and with clipping for different values of CR.
no clipping
CR = 1dB
CR = 5dB
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independent input symbols x1,x2,x3......... . Then, the received signal y can be
written in a matrix form as follows.
Y= (31)
where (z=z1,z2,z3.......... T
is a noise vector which is assumed to be zero mean
circular symmetric complex Gaussian (ZMCSCG). The autocorrelation of transmitted
signal vector is given by
(32)
The capacity of a deterministic channel is defined as
bits/channel use in which f(x) is the probability density function (PDF) of the transmit
signal vector x, and is the mutual information of random vectors x and y.
From the fundamental principle of the information theory, the mutual information of
the two continuous random vectors x and y is given as
(33)
in which H(y) is the differential entropy of y and is the conditional
differential entropy of y when x is given. Using the statistical independence of the two
random vectors z and x in Equation 31, we can write equation 33 as follows
(34)
From the equation 33 we observe that H(z) is a constant, we can see that the
mutual information is maximized when H(y) is maximized. Now, the auto-correlation
matrix of y is given as
(35)
Putting the value of equation 31 in equation 35 we find
(36)
where, Ex the energy of the transmitted signals and N0 is the power spectral density of
the additive noise The differential entropy H(y) is maximized when y is
ZMCSCG which consequently requires x to be ZMCSCG. The mutual information
can be found from equation 34 as follows
= + ) bps/Hz (37)
Then, the channel capacity of deterministic MIMO channel in the case of CSI
known to both receiver and transmitter side is expressed as
bps/Hz (38)
When H is not known at the transmitter side, one can spread the energy equally
among all the transmit antennas so that the autocorrelation function of the transmit
signal vector x is given as
(39)
Finally the channel capacity is given as
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+ )
(40)
where r=min(NT,NR) denotes the rank of H and denotes the ith
eigen value.
4.2.1 Performance of Deterministic MIMO Channel Capacity
The performance of deterministic channel capacity per unit bandwidth is evaluated as
a function of SNR. In this simulation, a highly scattered environment is considered.
The capacity of a MIMO channel is analyzed with the antenna configuration as shown
in Table 3 below. Each channel is considered as a parallel flat fading channel. The
power in a parallel channel (after decomposition) is distributed as water filling
algorithm. Channel matrix H is measured using Rayleigh distribution function.
Table3 Antenna Configuration for MIMO channel capacity
Combination No of Transmitting
antennas
No of Receiving
antennas
1 2 2
2 3 3
3 4 4
4 5 5
This simulation computes channel capacity and PDF of elements in SVD of
matrix H, by varying the SNR from -10 dB to 20 dB, where 104 iterations are
performed.
Figure 6 Deterministic MIMO Channel Capacity in Terms of SNR
4.3 Ergodic Channel Capacity of MIMO-OFDM System
In general case, MIMO channels change randomly and hence is a random matrix
which means that its channel capacity is also randomly time varying and follows an
ergodic process in practice Then, we consider the following statistical notion of the
MIMO channel capacity.
bps/Hz (41)
-10 -5 0 5 10 15 20
0
5
10
15
20
25
30
SNR in dB
ChannelCapacity(bps/Hz)
Deterministic MIMO Channel Capacity in Terms of SNR
nt=2, nr=2
nt=3, nr=3
nt=4, nr=4
nt=5, nr=5
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which is frequently known as an ergodic channel capacity. The ergodic channel
capacity for the open-loop system without using CSI at the transmitter side from
equation 41 is given as
)} (42)
Similarly, the ergodic channel capacity for the closed loop (CL) system using CSI
at the transmitter side is given as
) (43)
Sometimes the ergodic channel capacity is expressed as a function of the outage
channel capacity. The outage probability can be defined as
(44)
4.3.1 Performance of Ergodic MIMO Channel Capacity
The performance of ergodic MIMO channel capacity per unit bandwidth is evaluated
as a function of SNR. Cumulative density function is also evaluated for ergodic
channel capacity.
Figure 7 Ergodic MIMO Channel Capacity in Terms of SNR
4.4 Capacity of MIMO Correlated Fading Channel
In general, the MIMO channel gains are not independent and identically distributed
(i.i.d.) and the capacity of the MIMO channel are closely related to the channel
correlation. For this reason, consider the capacity of the MIMO channel when the
channel gains between transmit and received antennas are correlated. We model the
correlated channel as follows:
(45)
Where Hw denotes the independent and identically distributed (i.i.d) Rayleigh fading
channel gain matrix and Rt is the correlation matrix taking correlations between the
transmit antennas, Rr is the correlation matrix taking correlations between the receive
antennas. Then the correlated channel capacity can be represented as
) (46)
-10 -5 0 5 10 15 20 25
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
X
F(X)
Empirical CDF
NT=NR=1
NT=NR=2
NT=NR=3
NT=NR=4
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From the above equations, let us consider two cases for simulation.
Case1: Correlation exists between transmit and receive antennas, transmit
antennas and receive antennas but the correlation matrix Rt and Rr are identical
Figure 8 Capacity of i.i.d and Correlated Channel in Terms of SNR with Correlation exist
between the Transmit Antennas and Receive Antennas but Same Correlation Matrix
Observation: Figure8 shows the capacity of i.i.d and correlated channel in terms of
SNR with correlation exists between the transmit antennas and receive antennas but
same correlation matrix. From figure 8 I observe that at 15 dB of SNR value 4×4 i.i.d
channel provide 16.22 bps/Hz whereas 3×3 i.i.d channel provides 11.8 bps/Hz and
4×4 correlated channel provides12.34 bps/Hz. So i.i.d channel outperforms the
correlated channel.
Case 2: Correlation exists between transmit and receive antennas, transmit
antennas and receive antennas but the correlation matrix Rt and Rr are not identical.
Figure 9 Capacity of i.i.d and Correlated Channel in Terms of SNR with Correlation Exists
between the Transmit Antennas and Receive Antennas but different Correlation Matrix
Observation:
Figure 9 shows the capacity of i.i.d and correlated channel in terms of SNR with
correlation exists between the transmit antennas and receive antennas but different
-10 -5 0 5 10 15 20
0
5
10
15
20
25
SNR in dB
ChannelCapacity(bps/Hz)
Capacity of i.i.d and Correlated Channel in Terms of SNR with Correlation Exists between the Transmit Antennas and Receive Antennas but Same Correlation Matrix
3×3 correlated channel
3×3 i.i.d channel
4×4 i.i.d channel
4×4 correlated channel
-10 -5 0 5 10 15 20
0
5
10
15
20
25
SNR in dB
ChannelCapacity(bps/Hz)
Capacity of i.i.d and Correlated Channel in terms of SNR with Correlation Exists between the Transmit Antennas and Receive Antennas but Different Correlation Matrix
3×3 correlated channel
3×3 i.i.d channel
4×4 correlated channel
4×4 i.i.d channel
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correlation matrix. In this case I noticed that 4×4 i.i.d channel provide 22bps/Hz
whereas 4×4 correlated channel provides 14 bps /Hz. So i.i.d channel outperforms the
correlated channel.
5. CONCLUSION
The performance of the ASTBC based MIMO OFDM system under Rayleigh fading
channel is evaluated and it is observed that the performance of two transmit antennas
with more receive antennas is much better than that of the system with two transmit
antenna and less receive antennas in term of BER due to the more diversity gain of
Alamouti’s code. The performance of deterministic, ergodic and correlated MIMO
channel capacity is evaluated. It is observed that the channel capacity increases with
the number of antennas added to the system, independent and identically distributed
channel outperforms the correlated channel. Finally, to reduce PAPR clipping
technique is applied and I observed that as the CR is reduced, the CL is lowered down
and more parts of the OFDM signal are clipped and hence, the BER is increasing and
the empirical CCDF is decreasing.
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