International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
On Channel Estimation of OFDM-BPSK and -QPSK over Nakagami-m Fading ChannelsCSCJournals
This paper evaluates the performance of OFDM - BPSK & -QPSK based system with and without channel estimation over Nakagami-m fading channels. Nakagami-m variants are generated by decomposition of Nakagami random variable into orthogonal random variables with Gaussian distribution envelopes. Performance of OFDM system in Nakagami channel has been reported here. The results yield the optimum value of m based on BER and SNR. Using this optimum value of m, Channel estimation over flat fading has been reported here. It has been depicted clearly from simulated graphs that channel estimation has further reduced the BER. However, threshold value of m has played a vital role during channel estimation.
Performance evaluation of high mobility OFDM channel estimation techniques IJECEIAES
In wireless communication, Orthogonal Frequency Division Multiplexing (OFDM) has been adopted due to its robustness to multipath fading and high data rate transmissions. At the other hand, the performance of OFDM systems severely degraded due to multi-path fading and Doppler frequency shifts in mobile systems, which causes inter-carrier-interference (ICI). Thus, Estimation of channel parameters is required at the receiver using a pre designed estimator where pilot tones are inserted in each OFDM symbol. In this paper, a random pilot data are generated and inserted in each OFDM symbol at equally spaced locations. The performance test of Least Square (LS) and Linear Minimum Mean Square (LMMSE) estimation methods are proposed with Discrete Fourier Transform (DFT) based on both LS and LMMSE, where different ITU channel models are considered in order to compare their performance for data transmission in high mobile systems with different Doppler frequencies exceeds 200 Hz and minimal number of pilots.
Orthogonal Frequency Division Multiplexing (OFDM) is of great interest for the development of
the fifth-generation technology. It is the cornerstone of Multiple-input multiple-output (MIMO) systems.
Even though inter carrier interference (ICI) and inter symbol interference (ISI) have been processed for
the fourth-generation standards, they still present a huge problem for the fifth-generation standards. This
paper explores the tradeoff between the length of the cyclic prefix and the performances of the OFDM
system. It also studies the effect of carrier frequency offset (CFO) on OFDM systems. A blind frequency
offset estimator that uses the correlations between the remodulated sequence in the receiver side and
the conventional received symbol is presented and a closed form solution is derived. The proposed
estimator is derived under short interval when the correlation is high, so it has low computational
complexity. Lin and Beek’s estimators are used for comparison. Simulations demonstrate the effectiveness
of the proposed estimator under Rayleigh fading channel.
Blind channel estimation for mimo ofdm systemstrungquang0207
This document presents a blind channel estimation technique for MIMO-OFDM systems. It generalizes existing subspace-based methods for single-input single-output OFDM systems to operate with multiple transmit and receive antennas. The proposed method establishes conditions for channel identifiability. It obtains accurate channel estimates using a small number of OFDM symbols and is insensitive to overestimates of the true channel order. The method can work with no or insufficient cyclic prefix if virtual carriers are present, potentially increasing channel utilization. Simulation results show the mean-square error performance of the proposed method.
Hybrid Adaptive Channel Estimation Technique in Time and Frequency Domain for...Tamilarasan N
This document summarizes a research paper that proposes a hybrid adaptive channel estimation technique for MIMO-OFDM wireless communication systems. The technique integrates channel estimation in the time domain and frequency domain. It uses column-based time domain estimation initially and switches to row-based frequency domain estimation when channel quality is good and bit error rate is low. It switches back to time domain estimation when channel quality worsens. The goal is to adaptively estimate the channel under different conditions. Experimental results showed the proposed hybrid technique outperformed other methods.
Classical Discrete-Time Fourier TransformBased Channel Estimation for MIMO-OF...IJCSEA Journal
In this document, we look at various time domain channel estimation methods with this constraint of null carriers at spectrumborders.We showin detail howto gauge the importance of the “border effect” depending on the number of null carriers, which may vary from one system to another. Thereby we assess the limit of the technique discussed when the number of null carriers is large. Finally the DFT with the truncated singular value decomposition (SVD) technique is proposed to completely eliminate the impact of the null subcarriers whatever their number. A technique for the determination of the truncation threshold for any MIMO-OFDM system is also proposed.
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.
On Channel Estimation of OFDM-BPSK and -QPSK over Nakagami-m Fading ChannelsCSCJournals
This paper evaluates the performance of OFDM - BPSK & -QPSK based system with and without channel estimation over Nakagami-m fading channels. Nakagami-m variants are generated by decomposition of Nakagami random variable into orthogonal random variables with Gaussian distribution envelopes. Performance of OFDM system in Nakagami channel has been reported here. The results yield the optimum value of m based on BER and SNR. Using this optimum value of m, Channel estimation over flat fading has been reported here. It has been depicted clearly from simulated graphs that channel estimation has further reduced the BER. However, threshold value of m has played a vital role during channel estimation.
Performance evaluation of high mobility OFDM channel estimation techniques IJECEIAES
In wireless communication, Orthogonal Frequency Division Multiplexing (OFDM) has been adopted due to its robustness to multipath fading and high data rate transmissions. At the other hand, the performance of OFDM systems severely degraded due to multi-path fading and Doppler frequency shifts in mobile systems, which causes inter-carrier-interference (ICI). Thus, Estimation of channel parameters is required at the receiver using a pre designed estimator where pilot tones are inserted in each OFDM symbol. In this paper, a random pilot data are generated and inserted in each OFDM symbol at equally spaced locations. The performance test of Least Square (LS) and Linear Minimum Mean Square (LMMSE) estimation methods are proposed with Discrete Fourier Transform (DFT) based on both LS and LMMSE, where different ITU channel models are considered in order to compare their performance for data transmission in high mobile systems with different Doppler frequencies exceeds 200 Hz and minimal number of pilots.
Orthogonal Frequency Division Multiplexing (OFDM) is of great interest for the development of
the fifth-generation technology. It is the cornerstone of Multiple-input multiple-output (MIMO) systems.
Even though inter carrier interference (ICI) and inter symbol interference (ISI) have been processed for
the fourth-generation standards, they still present a huge problem for the fifth-generation standards. This
paper explores the tradeoff between the length of the cyclic prefix and the performances of the OFDM
system. It also studies the effect of carrier frequency offset (CFO) on OFDM systems. A blind frequency
offset estimator that uses the correlations between the remodulated sequence in the receiver side and
the conventional received symbol is presented and a closed form solution is derived. The proposed
estimator is derived under short interval when the correlation is high, so it has low computational
complexity. Lin and Beek’s estimators are used for comparison. Simulations demonstrate the effectiveness
of the proposed estimator under Rayleigh fading channel.
Blind channel estimation for mimo ofdm systemstrungquang0207
This document presents a blind channel estimation technique for MIMO-OFDM systems. It generalizes existing subspace-based methods for single-input single-output OFDM systems to operate with multiple transmit and receive antennas. The proposed method establishes conditions for channel identifiability. It obtains accurate channel estimates using a small number of OFDM symbols and is insensitive to overestimates of the true channel order. The method can work with no or insufficient cyclic prefix if virtual carriers are present, potentially increasing channel utilization. Simulation results show the mean-square error performance of the proposed method.
Hybrid Adaptive Channel Estimation Technique in Time and Frequency Domain for...Tamilarasan N
This document summarizes a research paper that proposes a hybrid adaptive channel estimation technique for MIMO-OFDM wireless communication systems. The technique integrates channel estimation in the time domain and frequency domain. It uses column-based time domain estimation initially and switches to row-based frequency domain estimation when channel quality is good and bit error rate is low. It switches back to time domain estimation when channel quality worsens. The goal is to adaptively estimate the channel under different conditions. Experimental results showed the proposed hybrid technique outperformed other methods.
Classical Discrete-Time Fourier TransformBased Channel Estimation for MIMO-OF...IJCSEA Journal
In this document, we look at various time domain channel estimation methods with this constraint of null carriers at spectrumborders.We showin detail howto gauge the importance of the “border effect” depending on the number of null carriers, which may vary from one system to another. Thereby we assess the limit of the technique discussed when the number of null carriers is large. Finally the DFT with the truncated singular value decomposition (SVD) technique is proposed to completely eliminate the impact of the null subcarriers whatever their number. A technique for the determination of the truncation threshold for any MIMO-OFDM system is also proposed.
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.
The document proposes a novel joint carrier frequency offset (CFO) and channel estimation scheme for MIMO-OFDM systems using recursive least squares (RLS) algorithms. It first introduces a joint CFO and channel estimator using two iterative RLS algorithms. It then derives a more precise pilot-aided RLS algorithm to estimate residual CFO errors and enhance channel estimation accuracy. Simulation results show the proposed estimation scheme achieves fast convergence and performance close to theoretical bounds for a wide range of signal-to-noise ratios and an initial CFO up to half the subcarrier spacing.
Improved Ad-Hoc Networks Using Cooperative DiversityIJCSIT Journal
In this paper an ad-hoc network having source, a
destination and a third station which is a relay is analyzed.
The channels used here are modeled having thermal noise,
Rayleigh fading and path loss. Different methods for
combining and diversity protocols are compared.
Implementation of channel estimation algorithms in ofdm for 64 subcarriersIAEME Publication
The document discusses channel estimation algorithms in OFDM systems with 64 subcarriers. It compares the performance of least squares (LS), linear minimum mean square error (LMMSE), and modified MMSE channel estimation algorithms for different modulation schemes including PSK and QAM. Simulation results show that the modified MMMSE algorithm, which considers a reduced channel correlation matrix, achieves a lower symbol error rate than LS and LMMSE, especially at high SNRs, with reduced computational complexity compared to LMMSE.
This document discusses using Gamma tone Frequency Cepstral Coefficients (GFCC) and K-means clustering to identify singers based on their voice. It begins by explaining that MFCC is not accurate in noisy environments, while GFCC performs well in both clean and noisy audio. The process involves extracting GFCC features from the audio, using K-means clustering to group similar voices into clusters, and dynamic time warping for authentication. Feature extraction with GFCC involves preprocessing, framing, windowing, computing the discrete Fourier transform, applying a gamma tone filter bank, logarithmic compression, and discrete cosine transformation to generate feature vectors. K-means clustering is then used to group the feature vectors from similar voices into clusters to identify
This document summarizes a study that compares different methods for estimating the power delay profile (PDP) in MIMO-OFDM systems. It proposes a new method for PDP estimation that aims to mitigate noise and improve accuracy with limited sample sizes. The key steps of the proposed method are: 1) estimating the channel impulse response from pilot subcarriers, 2) deriving samples from the estimated channel response to estimate the PDP, 3) mitigating residual noise in the estimate by detecting and averaging noise at zero taps, and 4) using the estimated PDP in an LMMSE channel estimator. Simulation results show that the proposed method approaches the performance of Wiener filtering and provides better SNR than using a constant PDP estimate
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.
This document proposes using a Markov chain model and bipartite graphing to efficiently schedule spectrum in cognitive radio networks. It models the cognitive radio network as a k-connected bipartite graph and uses a Markov chain to represent the state transitions of channels between idle and busy. It then applies the Banker's algorithm to the modeled cognitive radio network to allocate spectrum to users while avoiding deadlock. The proposed approach indicates it could improve spectrum scheduling and allocation performance in cognitive radio networks.
Sparse channel estimation by pilot allocation in MIMO-OFDM systems IRJET Journal
This document summarizes research on sparse channel estimation techniques for MIMO-OFDM systems using compressed sensing theory. It describes how compressed sensing algorithms like Subspace Pursuit (SP) and CoSaMP can provide better channel estimation performance than conventional techniques like least squares estimation. SP and CoSaMP are greedy algorithms that iteratively select columns from the measurement matrix to minimize mean square error. Simulation results showed these compressed sensing algorithms reduce mean square error and bit error rate compared to normal channel estimation.
This paper aims, a 3D-Pilot Aided Multi-Input Multi-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) Channel Estimation (CE) for Digital Video Broadcasting -T2 (DVB-T2) for the 5 different proposed block and comb pilot patterns model and performed on different antenna configuration. The effects of multi-transceiver antenna on channel estimation are addressed with different pilot position in frequency, time and the vertical direction of spatial domain framing. This paper first focus on designing of 5-different proposed spatial correlated pilot pattern model with optimization of pilot overhead. Then it demonstrates the performance comparison of Least Square (LS) & Linear Minimum Mean Square Error (LMMSE), two linear channel estimators for 3D-Pilot Aided patterns on different antenna configurations in terms of Bit Error Rate. The simulation results are shown for Rayleigh fading noise channel environments. Also, 3x4 MIMO configuration is recommended as the most suitable configuration in this noise channel environments.
A Subspace Method for Blind Channel Estimation in CP-free OFDM SystemsCSCJournals
In this paper, a subspace method is proposed for blind channel estimation in orthogonal frequency-division multiplexing (OFDM) systems over time-dispersive channel. The proposed method does not require a cyclic prefix (CP) and thus leading to higher spectral efficiency. By exploiting the block Toeplitz structure of the channel matrix, the proposed blind estimation method performs satisfactorily with very few received OFDM blocks. Numerical simulations demonstrate the superior performance of the proposed algorithm over methods reported earlier in the literature.
Method for Converter Synchronization with RF InjectionCSCJournals
This paper presents an injection method for synchronizing analog to digital converters (ADC). This approach can eliminate the need for precision routed discrete synchronization signals of current technologies, such as JESD204. By eliminating the setup and hold time requirements at the conversion (or near conversion) clock rate, higher sample rate systems can be synchronized. Measured data from an existing multiple ADC conversion system was used to evaluate the method. Coherent beams were simulated to measure the effectiveness of the method. The results show near theoretical coherent processing gain.
This report discusses the planning Associate in
nursing the implementation of an OFDM system
in several information module schemes like MQPSK,
M-QAM. First, a short introduction is
provided by explaining the background and the
specification of the project. Then the report deals
with the system model, every block of the OFDM
system is represented (IFFT, FFT, Cyclic prefix,
modulation / reception, Channel estimation, bit
error rate). System design is analyzed. The
transmission techniques, further because the
system parameters for transmission and reception
are explained well. Finally, the results are
provided.
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 SEMI BLIND CHANNEL ESTIMATION METHOD BASED ON HYBRID NEURAL NETWORKS FOR UP...ijwmn
The paper describes how to improve channel estimation in Single Carrier Frequency Division Multiple
Access (SC-FDMA) system, using a Hybrid Artificial Neural Networks (HANN). The 3rd Generation
Partnership Project (3GPP) standards for uplink Long Term Evolution Advanced (LTE-A) uses pilot based
channel estimation technique. This kind of channel estimation method suffers from a considerable loss
ofbitrate due to pilot insertion; all data frame sent contains reference signal. The HANN converts data
aided channel estimator to semi blind channel estimator. To increase convergence speed, HANN uses some
channel propagation Fuzzy Rules to initialize Neural Network parameters before learning instead of a
random initialization, so its learning phase ismore rapidly compared to classic ANN.HANN allows more
bandwidth efficient and less complexity. Simulation results show that HANN has better computational
efficiency than the Minimum Mean Square Error (MMSE) estimator and has faster convergence than
classic Neural Networks estimators.
Performance improvement for papr reduction in lte downlink system with ellipt...IJCNCJournal
This paper is concerned with the performance improvement of PAPR reduction of orthogonal frequency division multiplexing (OFDM) signal using amplitude clipping & filtering based design. Note that OFDM is one of the well adept multi-carrier multiplexing transmission scheme which has been implemented in long term evolution (LTE) downlink. Nonetheless peak to average power ratio (PAPR) is the more rattling problem with OFDM, consequently in this paper a reduction procedure of the PAPR by using amplitude clipping and filtering is proposed. Here we used IIR bandpass elliptic filter after amplitude clipping to
reduce the PAPR. The performance of the system in terms of bit error rate (BER) is also canvased as a new
filter based clipping method. Our results show that the proposed methodology of clipping method with the
IIR elliptic band pass filter significantly reduces the PAPR value.
MODIFIED LLL ALGORITHM WITH SHIFTED START COLUMN FOR COMPLEXITY REDUCTIONijwmn
Multiple-input multiple-output (MIMO) systems are playing an important role in the recent wireless
communication. The complexity of the different systems models challenge different researches to get a good
complexity to performance balance. Lattices Reduction Techniques and Lenstra-Lenstra-Lovàsz (LLL)
algorithm bring more resources to investigate and can contribute to the complexity reduction purposes.
In this paper, we are looking to modify the LLL algorithm to reduce the computation operations by
exploiting the structure of the upper triangular matrix without “big” performance degradation. Basically,
the first columns of the upper triangular matrix contain many zeroes, so the algorithm will perform several
operations with very limited income. We are presenting a performance and complexity study and our
proposal show that we can gain in term of complexity while the performance results remains almost the
same.
Performance of Multiple symbol representation with clipping scheme for PAPR r...ijsrd.com
OFDM is one of the multicarrier modulation technique used in various communication systems. The major problem one faces while implementing this system is the high peak to average power .For an efficient OFDM system this PAPR should be low. In this paper a hybrid PAPR (peak to average power ratio) reduction technique for the OFDM (orthogonal frequency division multiplexing) signal which combines a multiple symbol representations method with a signal clipping method is proposed. In multiple symbol representations alternative signaling points are used to represent one symbol and PAPR is further reduced with the clipping scheme. The performance of the hybrid scheme is compared with the partial transmit sequence which is one of the other PAPR reduction scheme. In partial transmit sequence the input data is divided in to disjoint blocks transformed in to time domain sequence and rotated by phase factors. Theoretical analysis and simulation results validate that the proposed scheme has the ability to provide large PAPR reduction, low bit error rate. Performance analysis is also done with the partial transmit sequence scheme.
NEW BER ANALYSIS OF OFDM SYSTEM OVER NAKAGAMI-n (RICE) FADING CHANNELijcseit
Modern wireless communication systems support high speed multimedia services. These services require
high data rates with acceptable error rates. Orthogonal Frequency Division Multiplexing (OFDM) is a
capable candidate to solve this problem. In this paper, a new expression for the BER of OFDM system has
been derived over Nakagami–n (Rice) fading channels using characteristics function (CHF) approach. The
exact probability density function of first order of Nakagami-n (Rice) random vector is used to derive the
expression for the error rates of OFDM system. The BER derivation of Rician fading channel is slightly
more complex compared to the Nakagami–m distribution because the PDF of the Rician RV contains an
explicit term of a modified Bessel function of first kind. Earlier, this problem was solved by replacing the
Bessel function with its infinite series and exponential integral representation. Here we propose an integral
expression to remove the complexity of the expression.
Revista brazilian journal of analytical chemistry - 1patfrg
The Brazilian Journal of Analytical Chemistry (BrJAC) is launching to promote discussion around the role of analytical chemistry in Brazil's development. BrJAC will publish scientific papers and editorials to foster academic-industrial integration and innovation. Analytical chemistry is important as technological innovation plays a larger role in public policy and business in Brazil. The journal aims to help change Brazil's scenario where most PhD students remain in academia rather than working in industry.
This document presents a comparative study of three microstrip patch antennas - square, circular, and equilateral triangular - for wireless local area network (WLAN) applications. The antennas were designed to operate at 3.5 GHz using a low-cost glass epoxy substrate. Results showed that all three antennas exhibited broadside radiation patterns. Measurement data indicated that the square patch antenna achieved the highest gain of 0.8 dB and bandwidth of 2.94%, making it most suitable for WLAN applications. Overall, this study evaluates different patch antenna geometries to help antenna designers select options for specific use cases.
The document proposes a novel joint carrier frequency offset (CFO) and channel estimation scheme for MIMO-OFDM systems using recursive least squares (RLS) algorithms. It first introduces a joint CFO and channel estimator using two iterative RLS algorithms. It then derives a more precise pilot-aided RLS algorithm to estimate residual CFO errors and enhance channel estimation accuracy. Simulation results show the proposed estimation scheme achieves fast convergence and performance close to theoretical bounds for a wide range of signal-to-noise ratios and an initial CFO up to half the subcarrier spacing.
Improved Ad-Hoc Networks Using Cooperative DiversityIJCSIT Journal
In this paper an ad-hoc network having source, a
destination and a third station which is a relay is analyzed.
The channels used here are modeled having thermal noise,
Rayleigh fading and path loss. Different methods for
combining and diversity protocols are compared.
Implementation of channel estimation algorithms in ofdm for 64 subcarriersIAEME Publication
The document discusses channel estimation algorithms in OFDM systems with 64 subcarriers. It compares the performance of least squares (LS), linear minimum mean square error (LMMSE), and modified MMSE channel estimation algorithms for different modulation schemes including PSK and QAM. Simulation results show that the modified MMMSE algorithm, which considers a reduced channel correlation matrix, achieves a lower symbol error rate than LS and LMMSE, especially at high SNRs, with reduced computational complexity compared to LMMSE.
This document discusses using Gamma tone Frequency Cepstral Coefficients (GFCC) and K-means clustering to identify singers based on their voice. It begins by explaining that MFCC is not accurate in noisy environments, while GFCC performs well in both clean and noisy audio. The process involves extracting GFCC features from the audio, using K-means clustering to group similar voices into clusters, and dynamic time warping for authentication. Feature extraction with GFCC involves preprocessing, framing, windowing, computing the discrete Fourier transform, applying a gamma tone filter bank, logarithmic compression, and discrete cosine transformation to generate feature vectors. K-means clustering is then used to group the feature vectors from similar voices into clusters to identify
This document summarizes a study that compares different methods for estimating the power delay profile (PDP) in MIMO-OFDM systems. It proposes a new method for PDP estimation that aims to mitigate noise and improve accuracy with limited sample sizes. The key steps of the proposed method are: 1) estimating the channel impulse response from pilot subcarriers, 2) deriving samples from the estimated channel response to estimate the PDP, 3) mitigating residual noise in the estimate by detecting and averaging noise at zero taps, and 4) using the estimated PDP in an LMMSE channel estimator. Simulation results show that the proposed method approaches the performance of Wiener filtering and provides better SNR than using a constant PDP estimate
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.
This document proposes using a Markov chain model and bipartite graphing to efficiently schedule spectrum in cognitive radio networks. It models the cognitive radio network as a k-connected bipartite graph and uses a Markov chain to represent the state transitions of channels between idle and busy. It then applies the Banker's algorithm to the modeled cognitive radio network to allocate spectrum to users while avoiding deadlock. The proposed approach indicates it could improve spectrum scheduling and allocation performance in cognitive radio networks.
Sparse channel estimation by pilot allocation in MIMO-OFDM systems IRJET Journal
This document summarizes research on sparse channel estimation techniques for MIMO-OFDM systems using compressed sensing theory. It describes how compressed sensing algorithms like Subspace Pursuit (SP) and CoSaMP can provide better channel estimation performance than conventional techniques like least squares estimation. SP and CoSaMP are greedy algorithms that iteratively select columns from the measurement matrix to minimize mean square error. Simulation results showed these compressed sensing algorithms reduce mean square error and bit error rate compared to normal channel estimation.
This paper aims, a 3D-Pilot Aided Multi-Input Multi-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) Channel Estimation (CE) for Digital Video Broadcasting -T2 (DVB-T2) for the 5 different proposed block and comb pilot patterns model and performed on different antenna configuration. The effects of multi-transceiver antenna on channel estimation are addressed with different pilot position in frequency, time and the vertical direction of spatial domain framing. This paper first focus on designing of 5-different proposed spatial correlated pilot pattern model with optimization of pilot overhead. Then it demonstrates the performance comparison of Least Square (LS) & Linear Minimum Mean Square Error (LMMSE), two linear channel estimators for 3D-Pilot Aided patterns on different antenna configurations in terms of Bit Error Rate. The simulation results are shown for Rayleigh fading noise channel environments. Also, 3x4 MIMO configuration is recommended as the most suitable configuration in this noise channel environments.
A Subspace Method for Blind Channel Estimation in CP-free OFDM SystemsCSCJournals
In this paper, a subspace method is proposed for blind channel estimation in orthogonal frequency-division multiplexing (OFDM) systems over time-dispersive channel. The proposed method does not require a cyclic prefix (CP) and thus leading to higher spectral efficiency. By exploiting the block Toeplitz structure of the channel matrix, the proposed blind estimation method performs satisfactorily with very few received OFDM blocks. Numerical simulations demonstrate the superior performance of the proposed algorithm over methods reported earlier in the literature.
Method for Converter Synchronization with RF InjectionCSCJournals
This paper presents an injection method for synchronizing analog to digital converters (ADC). This approach can eliminate the need for precision routed discrete synchronization signals of current technologies, such as JESD204. By eliminating the setup and hold time requirements at the conversion (or near conversion) clock rate, higher sample rate systems can be synchronized. Measured data from an existing multiple ADC conversion system was used to evaluate the method. Coherent beams were simulated to measure the effectiveness of the method. The results show near theoretical coherent processing gain.
This report discusses the planning Associate in
nursing the implementation of an OFDM system
in several information module schemes like MQPSK,
M-QAM. First, a short introduction is
provided by explaining the background and the
specification of the project. Then the report deals
with the system model, every block of the OFDM
system is represented (IFFT, FFT, Cyclic prefix,
modulation / reception, Channel estimation, bit
error rate). System design is analyzed. The
transmission techniques, further because the
system parameters for transmission and reception
are explained well. Finally, the results are
provided.
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 SEMI BLIND CHANNEL ESTIMATION METHOD BASED ON HYBRID NEURAL NETWORKS FOR UP...ijwmn
The paper describes how to improve channel estimation in Single Carrier Frequency Division Multiple
Access (SC-FDMA) system, using a Hybrid Artificial Neural Networks (HANN). The 3rd Generation
Partnership Project (3GPP) standards for uplink Long Term Evolution Advanced (LTE-A) uses pilot based
channel estimation technique. This kind of channel estimation method suffers from a considerable loss
ofbitrate due to pilot insertion; all data frame sent contains reference signal. The HANN converts data
aided channel estimator to semi blind channel estimator. To increase convergence speed, HANN uses some
channel propagation Fuzzy Rules to initialize Neural Network parameters before learning instead of a
random initialization, so its learning phase ismore rapidly compared to classic ANN.HANN allows more
bandwidth efficient and less complexity. Simulation results show that HANN has better computational
efficiency than the Minimum Mean Square Error (MMSE) estimator and has faster convergence than
classic Neural Networks estimators.
Performance improvement for papr reduction in lte downlink system with ellipt...IJCNCJournal
This paper is concerned with the performance improvement of PAPR reduction of orthogonal frequency division multiplexing (OFDM) signal using amplitude clipping & filtering based design. Note that OFDM is one of the well adept multi-carrier multiplexing transmission scheme which has been implemented in long term evolution (LTE) downlink. Nonetheless peak to average power ratio (PAPR) is the more rattling problem with OFDM, consequently in this paper a reduction procedure of the PAPR by using amplitude clipping and filtering is proposed. Here we used IIR bandpass elliptic filter after amplitude clipping to
reduce the PAPR. The performance of the system in terms of bit error rate (BER) is also canvased as a new
filter based clipping method. Our results show that the proposed methodology of clipping method with the
IIR elliptic band pass filter significantly reduces the PAPR value.
MODIFIED LLL ALGORITHM WITH SHIFTED START COLUMN FOR COMPLEXITY REDUCTIONijwmn
Multiple-input multiple-output (MIMO) systems are playing an important role in the recent wireless
communication. The complexity of the different systems models challenge different researches to get a good
complexity to performance balance. Lattices Reduction Techniques and Lenstra-Lenstra-Lovàsz (LLL)
algorithm bring more resources to investigate and can contribute to the complexity reduction purposes.
In this paper, we are looking to modify the LLL algorithm to reduce the computation operations by
exploiting the structure of the upper triangular matrix without “big” performance degradation. Basically,
the first columns of the upper triangular matrix contain many zeroes, so the algorithm will perform several
operations with very limited income. We are presenting a performance and complexity study and our
proposal show that we can gain in term of complexity while the performance results remains almost the
same.
Performance of Multiple symbol representation with clipping scheme for PAPR r...ijsrd.com
OFDM is one of the multicarrier modulation technique used in various communication systems. The major problem one faces while implementing this system is the high peak to average power .For an efficient OFDM system this PAPR should be low. In this paper a hybrid PAPR (peak to average power ratio) reduction technique for the OFDM (orthogonal frequency division multiplexing) signal which combines a multiple symbol representations method with a signal clipping method is proposed. In multiple symbol representations alternative signaling points are used to represent one symbol and PAPR is further reduced with the clipping scheme. The performance of the hybrid scheme is compared with the partial transmit sequence which is one of the other PAPR reduction scheme. In partial transmit sequence the input data is divided in to disjoint blocks transformed in to time domain sequence and rotated by phase factors. Theoretical analysis and simulation results validate that the proposed scheme has the ability to provide large PAPR reduction, low bit error rate. Performance analysis is also done with the partial transmit sequence scheme.
NEW BER ANALYSIS OF OFDM SYSTEM OVER NAKAGAMI-n (RICE) FADING CHANNELijcseit
Modern wireless communication systems support high speed multimedia services. These services require
high data rates with acceptable error rates. Orthogonal Frequency Division Multiplexing (OFDM) is a
capable candidate to solve this problem. In this paper, a new expression for the BER of OFDM system has
been derived over Nakagami–n (Rice) fading channels using characteristics function (CHF) approach. The
exact probability density function of first order of Nakagami-n (Rice) random vector is used to derive the
expression for the error rates of OFDM system. The BER derivation of Rician fading channel is slightly
more complex compared to the Nakagami–m distribution because the PDF of the Rician RV contains an
explicit term of a modified Bessel function of first kind. Earlier, this problem was solved by replacing the
Bessel function with its infinite series and exponential integral representation. Here we propose an integral
expression to remove the complexity of the expression.
Revista brazilian journal of analytical chemistry - 1patfrg
The Brazilian Journal of Analytical Chemistry (BrJAC) is launching to promote discussion around the role of analytical chemistry in Brazil's development. BrJAC will publish scientific papers and editorials to foster academic-industrial integration and innovation. Analytical chemistry is important as technological innovation plays a larger role in public policy and business in Brazil. The journal aims to help change Brazil's scenario where most PhD students remain in academia rather than working in industry.
This document presents a comparative study of three microstrip patch antennas - square, circular, and equilateral triangular - for wireless local area network (WLAN) applications. The antennas were designed to operate at 3.5 GHz using a low-cost glass epoxy substrate. Results showed that all three antennas exhibited broadside radiation patterns. Measurement data indicated that the square patch antenna achieved the highest gain of 0.8 dB and bandwidth of 2.94%, making it most suitable for WLAN applications. Overall, this study evaluates different patch antenna geometries to help antenna designers select options for specific use cases.
AdHoc Probe is a tool that estimates the effective end-to-end path capacity in wireless ad hoc networks. It employs a one-way active probing technique called packet pair dispersion that measures the minimum delay between two probing packets to estimate capacity without queueing effects. Simulations and testbed experiments using AdHoc Probe show it can accurately measure path capacity under different conditions such as varying topology, interference, mobility, and transmission rates in both single-hop and multi-hop wireless ad hoc network configurations.
This document defines the Open Virtualization Format (OVF) specification for packaging and distributing virtual appliances or machines. It specifies the structure of OVF packages, including an OVF descriptor file and associated files. The descriptor contains metadata about the virtual system, including a hardware profile, operating system, storage, networking, and installation requirements. The goal of the OVF format is to provide an open standard for packaging and distributing virtual systems.
This document summarizes a recommendation from the International Telecommunication Union (ITU) regarding traffic measurement data analysis. It discusses analyzing measurement data from telecommunication networks to support planning, engineering, and managing networks. The analysis can process data to remove unnecessary values, replace missing data, and calculate parameters. Analysis results like traffic data records and reports can then be used for applications like network dimensioning and performance monitoring.
Dynamic routing protocols share routing information between routers to automatically update routing tables when network changes occur and determine the best path. They are classified as interior gateway protocols, which route within an autonomous system, or exterior gateway protocols, which route between autonomous systems. Metrics like bandwidth and hop count are used to calculate the best path, while administrative distance indicates the priority of routes.
Pilot based channel estimation improvement in orthogonal frequency-division m...IJECEIAES
Pilot based least square (LS) channel estimation is a commonly used channel estimation technique in orthogonal frequency-division multiplexing based systems due to its simplicity. However, LS estimation does not handle the noise effect and hence suffers from performance degradation. Since the channel coefficients are correlated in time and hence show a slower variation than the noise, it is possible to encode the channel using linear predictive coding (LPC) without the noise. In this work, the channel is estimated from the pilots using LS estimation and in a second step the channel’s LS estimation is encoded as LPC coefficients to produce an improved channel estimation. The estimation technique is simulated for space-time block coding (STBC) based orthogonal frequency-division multiplexing (OFDM) system and the bit error rate (BER) curves show improvement of the LPC estimation over the LS estimation of the channel.
Iaetsd adaptive modulation in mimo ofdm system for4 gIaetsd Iaetsd
This paper proposes applying hybrid adaptation techniques in MIMO OFDM systems to improve spectral efficiency and reduce transmit power. It first analyzes the bit error rate of M-QAM modulation in OFDM systems with different numbers of subcarriers. Channel estimation is performed using MMSE, which estimates the channel with less error than LS. Feedback from channel estimation is then used with hybrid adaptation techniques. Simulation results show MMSE has lower MSE and symbol errors than LS estimation.
1) The document proposes simultaneous multi-channel reconstruction for TDS-OFDM based next-generation broadcasting systems using compressive sensing. It introduces several OFDM transmission schemes and issues with interference cancellation in TDS-OFDM.
2) It then describes a new algorithm called Simultaneous CoSaMP (S-CoSaMP) that exploits joint time-frequency processing to improve channel reconstruction over existing algorithms.
3) Simulation results show S-CoSaMP achieves higher signal recovery rates and lower estimation errors than other algorithms, demonstrating its effectiveness for supporting technologies like 256QAM.
Reduction of Frequency offset Using Joint Clock for OFDM Based Cellular Syste...IJRST Journal
This project addresses the problem of clock synchronization between a base station (BS) and a mobile station (MS). A conventional technique for clock synchronization is that the MS clock is derived from the downlink signal originated from a base station. In cellular systems, a base station and mobile stations need to be synchronized before data exchange. Since the base station clock reference is more accurate, a mobile station typically derives its clock reference from the base station. But the carrier frequency offset due to Doppler shift may have harmful effects on the local clock derivation. This project proposes a joint clock and frequency synchronization technique between a base station and a mobile station, which is effective even with Doppler shift. We derive the joint estimation algorithm by analyzing the phase and the amplitude distortion caused by the sampling frequency offset and the carrier frequency offset. Simulation results showing the effectiveness of the proposed algorithm will also be presented.
An Effective Approach for Colour Image Transmission using DWT Over OFDM for B...IJMTST Journal
Image transmission over the fading channels without degrading the perceptual quality is a challenging task while mitigating the power consumption in many fields such as broadband networks, mobile communications, Image sharing and video broadcasting. Also, it is not possible to resend the lost packets every time in many applications such as video broadcasting. Here, an effective approach for color image transmission has been proposed with power saving approach over OFDM system. Experimental results shows that the reception quality of received image is good enough with various peak signal to noise ratios also saved 60% of energy.
Performance evaluation of 4-quadrature amplitude modulation over orthogonal ...IJECEIAES
Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation (MCM) technique that divides the wide bandwidth into parallel narrow bands, each of which is modulated by orthogonal subcarriers. Currently, OFDM is a high-spectral efficiency modulation technique that is used in a variety of wired and wireless applications. The transmitted signal in a wireless communication channel spreads from transmitter to receiver through multiple reflective paths. This triggers multipath fading, which causes variations in the received signal's amplitude and phase. Slow/fast and frequency-selective/frequency-nonselective are the main types of multipath fading channels. Therefore, in this paper, we proposed new models for modeling multipath fading channels, such as the exponential fading channel and the Gamma fading channel. In addition, new bit-error-rate (BER) derivations have been derived. The performance of the OFDM system over proposed channel models has been evaluated using Monte-Carlo simulation and compared to the Rayleigh fading channel model. The obtained results via simulations show that the exponential fading channel at a rate parameter (λ=0.5) outperforms the Rayleigh fading channel by 6 dB for all values of Eb/No, while the Gamma fading channel at (α=2) outperforms the Rayleigh fading channel by 3 dB for all values of Eb/No.
Multi-carrier Equalization by Restoration of RedundancY (MERRY) for Adaptive ...IJNSA Journal
This paper proposes a new blind adaptive channel shortening approach for multi-carrier systems. The performance of the discrete Fourier transform-DMT (DFT-DMT) system is investigated with the proposed DST-DMT system over the standard carrier serving area (CSA) loop1. Enhanced bit rates demonstrated and less complexity also involved by the simulation of the DST-DMT system.
The document proposes a new channel estimation algorithm called ICEA-DA for MIMO-OFDM systems. ICEA-DA uses least squares estimation with discrete Fourier transform and integrates it with a differential evolution technique. It is placed at the central part of the MIMO-OFDM system between the transmitter and receiver blocks. The proposed method is evaluated for a 2x4 MIMO system using QPSK modulation. Results show ICEA-DA provides better performance than existing techniques in terms of bit error rate, peak signal-to-noise ratio, channel capacity, and symbol error rate.
Performance analysis of image transmission with various channel conditions/mo...TELKOMNIKA JOURNAL
This paper investigates the impact of different modulation techniques for
digital communication systems that employ quadrature phase shift keying
(QPSK) and quadrature amplitude modulation (16-QAM and 64-QAM) to
transmit images over AWGN and Rayleigh fading channels for the cellular
mobile networks. In the further steps, wiener and median filters has been
adopted to the simulation are used at the receiver side to remove the impulsive
noise present in the received image. This work is performed to evaluate
the transmission of two dimensional (2D) gray-scale and color-scale (RGB)
images with different values from signal to noise ratios (SNR), such as;
(5, 10 and 15) dB over different channels. The correct conclusions are made
by comparing many of the observed Matlab simulation results. This was
carried out through the results that measure the quality of received image,
which is analyzes in terms of SNRimage peak signal to noise ratio (PSNR) and
mean square error (MSE).
Performance enhancement of audio transmission based on LMMSE methodnooriasukmaningtyas
The research in wireless communication has developed rapidly for the last
decades as a result of raising the demand for efficient data transmission with
more security and accuracy. This paper proposed a system based on the
special multiplexing (SM) technique and linear minimum mean square error
(LMMSE) detection method with the assistance of the hamming code as well
as the interleaving techniques for a better enhanced performance of an audio
transmission. Moreover, the comparison was done between the two systems
for different antenna configurations and with the presence of two types of
modulation: binary phase shift key and quateradure phase shift key. These
systems are employed by Matlab simulation to show significant results in
terms of enhancing the Rayleigh fading channel capacity, bit error rate
(BER) and security as well as in recovering the transmitting audio signals.
Each system has advantages than the others in one performance term respect
to the other terms. The simulation results have provided to prove and discuss
our analysis.
This document provides an overview of channel estimation strategies used in orthogonal frequency division multiplexing (OFDM) systems. It describes the basic types of channel estimation methods: block-type pilot channel estimation and comb-type pilot channel estimation. For block-type estimation, pilots are inserted into all subcarriers of OFDM symbols periodically. This allows estimation of the channel conditions between pilot symbols. Estimation can be done with least squares (LS), minimum mean-square error (MMSE), or modified MMSE. For comb-type estimation, pilots are inserted into certain subcarriers of each symbol, requiring interpolation to estimate data subcarriers. The document compares the implementation complexity and performance of different estimation methods.
This document summarizes a research paper that proposes a modified channel shortener filter (MCSF) to improve the spectral efficiency of OFDM systems. The MCSF exploits the null space of an underdetermined system of equations to provide multiple independent equivalent channels to the receiver. It is shown that the MCSF can achieve a higher spectral efficiency than conventional OFDM when the cyclic prefix length is significantly smaller than the channel delay spread. Simulation results demonstrate that the MCSF improves bit error rate performance and can provide up to 2dB gain compared to full cyclic prefix OFDM systems. The MCSF has the potential to reduce receiver complexity compared to existing channel shortening approaches.
Estimation of bit error rate in 2×2 and 4×4 multi-input multioutput-orthogon...IJECEIAES
Multiple-input, multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems with multiple input antennas and multiple output antennas in dynamic environments face the challenge of channel estimation. To overcome this challenge and to improve the performance and signal-tonoise ratio, in this paper we used the Kalman filter for the correct estimation of the signal in dynamic environments. To obtain the original signal at the receiver end bit error rate factor plays a major role. If the signal to noise ratio is high and the bit error rate is low then signal strength is high, the signal received at the receiver end is almost similar to the i th transmitted signal. The dynamic tracking characteristic of Kalman filter is used to establish a dynamic space-time codeword and a collection of orthogonal pilot sequences to prevent interference among transmissions in this paper. Using the simulation, the Kalman filter method can be compared to the other channel estimation method presented in this paper that can track timevarying channels rapidly.
Analysis of cyclic prefix length effect on ISI limitation in OFDM system over...IJECEIAES
In this work, the influence of the cyclic prefix on the performance of the OFDM system is studied. We worked out an OFDM transceiver using a 16 QAM modulation scheme, a comparison of the BER for various lengths of the cyclic prefix has been achieved, and the influence of the noise introduced in the channel has been highlighted, for both a Gaussian and Rayleigh noise. The simulation was carried out on MATLAB where the curves of the BER for various lengths of the cyclic prefix are given and compared. We also adopted as a metric the QAM constellation to show the dispersion of the carriers as a consequence of the transmission channel, the mitigation of this effect by the CP is noticeable.
Comparative ber analysis of mitigation of ici through sc,ml and ekf methods i...IAEME Publication
This document summarizes a research paper that was published in the International Journal of Electronics and Communication Engineering & Technology. The paper investigates methods to mitigate inter-carrier interference (ICI) in OFDM systems, which is caused by frequency offsets. It compares the performance of three ICI mitigation techniques: self-cancellation, maximum likelihood estimation, and an extended Kalman filter method. Through simulations, the paper shows that these three techniques are effective at reducing the effects of ICI. For high frequency offsets and higher order modulation schemes, the maximum likelihood and extended Kalman filter methods perform better than self-cancellation.
Multi-Hop Routing Cooperative Communication for Improving Throughput in IEEE ...IJERA Editor
In this paper, we propose cooperative communication scheme using multiple relays to improve the throughput of IEEE 802.11x wireless LAN. The proposed scheme performs cooperative communication with a terminal supporting a high data rate in order to solve the problem that a total network throughput is greatly reduced when a terminal supporting a low data rate occupies a channel. Also, the multi-hop routing is performed to optimize the performance of cooperative communication. According to the simulation results, the proposed cooperative communication scheme improves the reduction rate of the throughput even if the number of terminals supporting a low data rate increases in the entire network
The document proposes a new adaptive channel estimation algorithm called Sign Data Sign Error Least Mean Square (SDSELMS) for MIMO-OFDM systems. SDSELMS aims to improve convergence rate and reduce computational complexity compared to existing algorithms like LMS, NLMS, SELMS, and SDNLMS. It applies the signum function to both the input data and error signals, requiring only one multiplication if both signals are non-zero. Simulation results show SDSELMS achieves a faster convergence rate than other algorithms while providing mean square error performance close to the optimal NLMS algorithm but with lower complexity.
Performance evaluation on the basis of bit error rate for different order of ...ijmnct
This document summarizes research evaluating the bit error rate (BER) for different modulation orders and subchannel lengths in an orthogonal frequency division multiplexing (OFDM) system. The research considers QPSK, 8-QAM, and 16-QAM modulation with 256, 512, and 4096 subchannels. Simulation results in MATLAB show that:
1) For 256 subchannels, QPSK modulation has the lowest BER across signal-to-noise ratio (SNR) values from 0-27dB.
2) BER increases with higher modulation orders (from QPSK to 16-QAM) for a given subchannel length.
3) The research provides a comparative analysis of BER performance in an OFDM system
Compressive sensing-based channel estimation for high mobile systems with del...TELKOMNIKA JOURNAL
In this paper, channel overhead is reduced by exploiting channel sparsity for multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) system. Where, compressive sensing (CS) based dictionary design algorithms has been adopted as a channel estimation technique in high mobile systems with minimal number of pilots, such as high-speed train (HST) systems. A novel framework design of the dictionary-based CS was proposed considering both delay and Doppler effects in order to correctly recover the channel response. The channel under consideration is a 2 by 2 space-time block code (STBC) MIMO channel. Simulation tests according to the international telecommunication union (ITU) channel model demonstrated the suitability of the proposed dictionary for estimating the channel impulse response (CIR) of a liner time varying (LTV) channel with a mobility approaches 675 Km/h related to a Doppler frequency of 1500 Hz and 2.4 GHz carrier frequency. Two CS recovery algorithms were applied; orthogonal matching pursuit (OMP) and basis pursuit (BP), where by about 7 dB gain in signal to noise ratio (SNR) was achieved with mobility of 675 Km/h using OMP as compared to BP at a bit error rate (BER) of with 128 OFDM subcarriers.
Similar to International Journal of Engineering and Science Invention (IJESI) (20)
Digital Marketing Trends in 2024 | Guide for Staying AheadWask
https://www.wask.co/ebooks/digital-marketing-trends-in-2024
Feeling lost in the digital marketing whirlwind of 2024? Technology is changing, consumer habits are evolving, and staying ahead of the curve feels like a never-ending pursuit. This e-book is your compass. Dive into actionable insights to handle the complexities of modern marketing. From hyper-personalization to the power of user-generated content, learn how to build long-term relationships with your audience and unlock the secrets to success in the ever-shifting digital landscape.
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
Digital Banking in the Cloud: How Citizens Bank Unlocked Their MainframePrecisely
Inconsistent user experience and siloed data, high costs, and changing customer expectations – Citizens Bank was experiencing these challenges while it was attempting to deliver a superior digital banking experience for its clients. Its core banking applications run on the mainframe and Citizens was using legacy utilities to get the critical mainframe data to feed customer-facing channels, like call centers, web, and mobile. Ultimately, this led to higher operating costs (MIPS), delayed response times, and longer time to market.
Ever-changing customer expectations demand more modern digital experiences, and the bank needed to find a solution that could provide real-time data to its customer channels with low latency and operating costs. Join this session to learn how Citizens is leveraging Precisely to replicate mainframe data to its customer channels and deliver on their “modern digital bank” experiences.
Trusted Execution Environment for Decentralized Process MiningLucaBarbaro3
Presentation of the paper "Trusted Execution Environment for Decentralized Process Mining" given during the CAiSE 2024 Conference in Cyprus on June 7, 2024.
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
An English 🇬🇧 translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
How to Interpret Trends in the Kalyan Rajdhani Mix Chart.pdfChart Kalyan
A Mix Chart displays historical data of numbers in a graphical or tabular form. The Kalyan Rajdhani Mix Chart specifically shows the results of a sequence of numbers over different periods.
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
In the realm of cybersecurity, offensive security practices act as a critical shield. By simulating real-world attacks in a controlled environment, these techniques expose vulnerabilities before malicious actors can exploit them. This proactive approach allows manufacturers to identify and fix weaknesses, significantly enhancing system security.
This presentation delves into the development of a system designed to mimic Galileo's Open Service signal using software-defined radio (SDR) technology. We'll begin with a foundational overview of both Global Navigation Satellite Systems (GNSS) and the intricacies of digital signal processing.
The presentation culminates in a live demonstration. We'll showcase the manipulation of Galileo's Open Service pilot signal, simulating an attack on various software and hardware systems. This practical demonstration serves to highlight the potential consequences of unaddressed vulnerabilities, emphasizing the importance of offensive security practices in safeguarding critical infrastructure.
TrustArc Webinar - 2024 Global Privacy SurveyTrustArc
How does your privacy program stack up against your peers? What challenges are privacy teams tackling and prioritizing in 2024?
In the fifth annual Global Privacy Benchmarks Survey, we asked over 1,800 global privacy professionals and business executives to share their perspectives on the current state of privacy inside and outside of their organizations. This year’s report focused on emerging areas of importance for privacy and compliance professionals, including considerations and implications of Artificial Intelligence (AI) technologies, building brand trust, and different approaches for achieving higher privacy competence scores.
See how organizational priorities and strategic approaches to data security and privacy are evolving around the globe.
This webinar will review:
- The top 10 privacy insights from the fifth annual Global Privacy Benchmarks Survey
- The top challenges for privacy leaders, practitioners, and organizations in 2024
- Key themes to consider in developing and maintaining your privacy program
Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
SAM4U, an SAP complimentary software asset management tool for customers, delivers a detailed and well-structured overview of license inventory and usage with a user-friendly interface. We offer a hosted, cost-effective, and performance-optimized SAM4U setup in the Skybuffer Cloud environment. You retain ownership of the system and data, while we manage the ABAP 7.58 infrastructure, ensuring fixed Total Cost of Ownership (TCO) and exceptional services through the SAP Fiori interface.
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
Dandelion Hashtable: beyond billion requests per second on a commodity serverAntonios Katsarakis
This slide deck presents DLHT, a concurrent in-memory hashtable. Despite efforts to optimize hashtables, that go as far as sacrificing core functionality, state-of-the-art designs still incur multiple memory accesses per request and block request processing in three cases. First, most hashtables block while waiting for data to be retrieved from memory. Second, open-addressing designs, which represent the current state-of-the-art, either cannot free index slots on deletes or must block all requests to do so. Third, index resizes block every request until all objects are copied to the new index. Defying folklore wisdom, DLHT forgoes open-addressing and adopts a fully-featured and memory-aware closed-addressing design based on bounded cache-line-chaining. This design offers lock-free index operations and deletes that free slots instantly, (2) completes most requests with a single memory access, (3) utilizes software prefetching to hide memory latencies, and (4) employs a novel non-blocking and parallel resizing. In a commodity server and a memory-resident workload, DLHT surpasses 1.6B requests per second and provides 3.5x (12x) the throughput of the state-of-the-art closed-addressing (open-addressing) resizable hashtable on Gets (Deletes).
zkStudyClub - LatticeFold: A Lattice-based Folding Scheme and its Application...Alex Pruden
Folding is a recent technique for building efficient recursive SNARKs. Several elegant folding protocols have been proposed, such as Nova, Supernova, Hypernova, Protostar, and others. However, all of them rely on an additively homomorphic commitment scheme based on discrete log, and are therefore not post-quantum secure. In this work we present LatticeFold, the first lattice-based folding protocol based on the Module SIS problem. This folding protocol naturally leads to an efficient recursive lattice-based SNARK and an efficient PCD scheme. LatticeFold supports folding low-degree relations, such as R1CS, as well as high-degree relations, such as CCS. The key challenge is to construct a secure folding protocol that works with the Ajtai commitment scheme. The difficulty, is ensuring that extracted witnesses are low norm through many rounds of folding. We present a novel technique using the sumcheck protocol to ensure that extracted witnesses are always low norm no matter how many rounds of folding are used. Our evaluation of the final proof system suggests that it is as performant as Hypernova, while providing post-quantum security.
Paper Link: https://eprint.iacr.org/2024/257
Taking AI to the Next Level in Manufacturing.pdfssuserfac0301
Read Taking AI to the Next Level in Manufacturing to gain insights on AI adoption in the manufacturing industry, such as:
1. How quickly AI is being implemented in manufacturing.
2. Which barriers stand in the way of AI adoption.
3. How data quality and governance form the backbone of AI.
4. Organizational processes and structures that may inhibit effective AI adoption.
6. Ideas and approaches to help build your organization's AI strategy.
Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...
International Journal of Engineering and Science Invention (IJESI)
1. International Journal of Engineering Science Invention
ISSN (Online): 2319 – 6734, ISSN (Print): 2319 – 6726
www.ijesi.org Volume 2 Issue 8 ǁ August 2013 ǁ PP.45-51
www.ijesi.org 45 | Page
Improving Channel Estimation in OFDM System Using Time
Domain Channel Estimation for Time Correlated Rayleigh
Fading Channel Model
Akhil Gupta
Department of Electronics & Communication Engineering, Jaypee University of Information Technology, India
ABSTRACT : In 4G and beyond systems, to achieve higher capacity with better performance, Orthogonal
Frequency Division Multiplexing (OFDM) is utilized. OFDM removes the deterioration in the channel due to
multipath fading. It converts the frequency selective fading channel into flat fading channel. In this paper,
improvement in channel estimation of OFDM system is shown in terms of Bit Error Rate (BER), Symbol Error
Rate (SER) and Mean Square Error (MSE). This paper also includes the effect of changing number of
subcarriers on the channel estimation performance. Improvement is shown between Least Square Error (LSE)
estimation, Minimum Mean Square Error (MMSE) estimation and time domain channel estimation techniques
i.e. Discrete Fourier Transform (DFT) and Discrete Cosine Transform (DCT) based channel estimation
techniques on time correlated Rayleigh fading channel model i.e. Dent channel model using the 16-QAM
modulation technique. Time domain channel estimation techniques are showing better performance with
minimum complexity than Least Square Error (LSE) estimation and Minimum Mean Square Error (MMSE)
estimation.
KEYWORDS –DCT, DFT, LSE, MMSE, OFDM
I. INTRODUCTION
The next generation of wireless communication demands for high data rate and better performance for
high rate audio and video applications. For high rate data streams, a problem due to inefficient utilization of
bandwidth and Inter Symbol Interference (ISI) has occurred. Orthogonal Frequency division multiplexing
(OFDM) utilizes the frequency spectrum in an efficient manner. It converts the high rate data streams to
multiple low rate data streams by allowing the orthogonal subcarriers to overlap each other. It converts the
frequency selective channel to flat fading channel. It uses the concept of cyclic prefix to remove the residual ISI
[1].
Better reliability and operation in a wireless system can be obtained by using error correcting schemes
and techniques utilized for multiple antenna system like space time block codes (STBC) and different diversity
techniques [2]. In order to enhance the performance of the above mentioned techniques, Channel state
information (CSI) is needed on the transmitter side. The efficient channel estimation technique will provide
better performance. Blind channel estimation technique is not suitable for wireless systems. Semi blind channel
estimation technique is preferred because it contains some of the information conveyed on the data in the form
of training symbols or pilots. They are added in the transmitted signal in block mode because it is suitable for
frequency selective channel [2].
Channel estimation can be done in both frequency and time domain. In frequency domain, Least
Square Error (LSE) channel estimation is performed. It has less complexity because it does not require any
information about the channel except the position of pilots, but it has degraded performance. Performance is
improved by using MMSE channel estimation but at the expense of an increase in complexity [3-5], since it uses
auto correlation matrices and noise variance of the channel.
Frequency domain channel estimation techniques are performing better but at the expense of high
complexity. So to increase the performance even further with less complexity, channel estimation is performed
in the time domain. DFT based channel estimation shows better performance with less complexity than
frequency domain channel estimation techniques. In this method, frequency domain estimated channel by LSE
estimation is converted to time domain by using Inverse Discrete Fourier Transform (IDFT). Then by applying
Spline interpolation, the noise is reduced in time domain by removing certain channel impulse response samples
which are profoundly impressed by the disturbance. Remaining samples are converted back to the frequency
2. Improving Channel Estimation in OFDM System Using …
www.ijesi.org 46 | Page
domain by using DFT. Thus by removing noise in time domain, performance is increased and complexity is
reduced because of the use of fast algorithms i.e. FFT and IFFT.
DFT based channel estimation has degraded efficiency for non-integer multipath samples which causes
frequency leakage and aliasing. To overcome this problem, another time domain channel estimation technique is
used which is DCT based channel estimation. In this method, as in image compression, it will form images of
the non-integer sample and removes the discontinuity between two samples. Time correlated Rayleigh fading
channel model i.e. the Dent channel model is used for realizing the improvement of channel estimation
performance in OFDM system using above mentioned estimation techniques.
The remaining paper is organized as follows. In section II, channel model is described. In section III,
channel estimation techniques are given and simulation results are given in section IV. The paper is concluded
in section V.
II. CHANNEL MODEL
In a wireless communication system, a signal is transmitted from transmitter to receiver through a
wireless channel. Due to the presence of various obstacles, multipath propagation occurs. The effect of this will
give rise to variation in the signal’s amplitude and phase causing multipath fading. The Rayleigh fading channel
model is one of the multipath fading channel models. It can be modeled by calculating the real and imaginary
components of the complex Gaussian channel. But for some cases only amplitude fluctuations of the Rayleigh
fading channel model are on our list.
Jakes proposed a deterministic method for modeling time correlated Rayleigh fading channel [6]. This
method is also known as the sum of sinusoidal signal model. In this model, a moving receiver receives M rays
of equal strength at uniformly distributed advent angle in such a way that the nth
ray will suffer a Doppler
shift of . But Jakes model has some problems that the different signals which are arriving at different angles
has a high correlation among each other, which is not desirable. Dent introduces the use of Walsh Hadamard
Code i.e. orthogonal codes to remove this correlation problem [6]. Another feature which helps to completely
remove the correlation is to allocate equal power to every oscillator. This condition is fulfilled by evaluating
Jakes model for distinct advent angles.
Taking and , the waveform can be described by:
(1)
Where l=1, 2… M0, M0=M/4, and are independent random phases which are
uniformly distributed in [0, 2 ). is the Walsh Hadamard codeword in m which satisfies the following
condition:
(2)
III. CHANNEL ESTIMATION
In this section, frequency domain channel estimation i.e. LSE and MMSE channel estimation and then
time domain channel estimation i.e. DFT and DCT based channel estimation method is explained.
1. Least Square Error (LSE) Channel Estimation
In this method, at the receiver side, the information about the position of the pilots in the transmitted
data (D) is known. With the information of received data (Z) and the position of the pilots, estimated channel
( ) can be calculated by minimizing the least square error:
(3)
Differentiate with respect to and then equate it to zero as shown:
(4)
3. Improving Channel Estimation in OFDM System Using …
www.ijesi.org 47 | Page
We have = which gives the solution to the LSE channel estimation given by:
(5)
This method shows poor performance but has less complexity because it does not require any
information about the channel.
2. Minimum Mean Square Error (MMSE) Channel Estimation
MMSE estimation of the channel H is given by [7]:
(6)
Where (7)
(8)
where is the auto covariance matrix of the received signal Z and is the cross covariance matrix
of channel H and received signal Z. is noise variance.
The estimated channel is given as:
(9)
where W matrix is used to switch channels from time domain to frequency domain. The P matrix is
given by [7]:
(10)
This method has better performance than LSE estimation but due to the use of auto covariance matrix
and noise variance values, complexity of the method increases.
3. Discrete Fourier Transform (DFT) based Channel Estimation
DFT based channel estimation is a time domain channel estimation technique. It is used to suppress the
noise in time domain because energy is concentrated in time domain. The main asset of this method is that it has
less complexity than LSE estimation because of the use of fast algorithms i.e. FFT and IFFT. Performance of
DFT based estimation is better than both LSE and MMSE estimation [8]. In this method, first the frequency
domain channel estimation is done using LSE channel estimation, which is given as:
(11)
Now estimated output is converted to time domain using the M-point IDFT.
(12)
In the time domain, energy is concentrated to only a small number of samples. Due to multipath fading,
a lot of samples in the channel which have lesser energy. So only L samples are considered which have a
considerable amount of energy than noise [9], so we set out:
(13)
After IDFT, zero padding is applied to increase the number of samples:
(14)
Since the channel response beyond L samples have only noise so this part can be cast aside. Only first
L samples are considered in DFT based channel estimation:
(15)
So DFT based channel estimation gives better performance because noise is removed in time domain
and has less complexity with the use of FFT and IFFT.
4. Discrete Cosine Transform (DCT) based Channel Estimation
In DFT based channel estimation, when DFT operation is applied to non-integer multiples of multipath
delays, there will be a problem of frequency leakage and thus cause aliasing. This is due to the discontinuity
4. Improving Channel Estimation in OFDM System Using …
www.ijesi.org 48 | Page
between two non-integer multiples. A windowing technique based DFT method can be used to remove this
problem. But by using this method, there occurs a decrease in spectral efficiency [10]. This problem can be
lessened by using another time domain channel estimation technique i.e. DCT based channel estimation. As in
image compression, DCT employs mirror extension of M-point data sequence which removes the discontinuous
edge. In this method, similar to DFT based channel estimation, firstly the channel is estimated by LSE channel
estimation. Then DCT operation is performed, is given in [11] and reproduced as follows:
(16)
Where
In the next step the zeros are inserted at the end of in the DCT domain:
(17)
After that extendible IDCT is applied to remove the shift effect produced by DCT in the time domain
which is given by [12] and reproduced as follows:
(18)
DCT based channel estimation removes the problem arises in DFT based channel estimation and
increase the performance even further.
IV. SIMULATION RESULTS
In this section, the channel estimation improvement in OFDM system is shown using LSE, MMSE,
DFT and DCT for a time correlated Rayleigh fading channel model (Dent channel model). The results are
plotted using MATLAB in terms of bit error rate, symbol error rate, mean square error and number of
subcarriers. The Dent channel model is simulated on an OFDM system using a 16-QAM modulation technique
and 512 point FFT. The simulation parameters are as shown in Table 1.
Table 1 Simulation Parameters
S.No. Parameters Values
1. Number of Subcarriers 512
2. Number of Symbols 100
3. Number of Pilots 4
4. Modulation Technique 16-QAM
5. Channel Model Dent
6. Speed(V) 100 KMPH
7. Central Carrier Frequency ( ) 2000 MHz
8. Symbol Frequency ( ) 10 KSPS
9. Number of Channel Coefficients(M) 16
1. Bit Error Rate (BER) Comparison
Figure 1 shows Comparison of BER performance of LSE estimation and DFT estimation technique. It
is clear from the figure 1 that DFT estimation technique shows better performance than LSE estimation
technique. At 24 dB SNR, bit error rate of DFT estimation is 8.7% less than LSE.
5. Improving Channel Estimation in OFDM System Using …
www.ijesi.org 49 | Page
Fig1. BER v/s SNR plot between LSE and DFT estimation techniques
2. Symbol Error Rate (SER) Comparison
Figure 2 shows Comparison of SER performance of LSE estimation and DFT estimation technique. It
is clear from the figure 2 that DFT estimation technique shows better performance than LSE estimation
technique. At 18 dB SNR, symbol error rate of DFT estimation is 7.7% less than LSE estimation.
Fig2. SER v/s SNR plot between LSE and DFT estimation techniques
3. Mean Square Error (MSE) Comparison
Figure 3 shows the performance comparison of all the channel estimation techniques. It is clear from
the figure 3 that DCT based channel estimation is showing better results than DFT based channel estimation. At
high SNR, the mean square error of MMSE with DCT increases due to high complexity and mean square error
of MMSE with DFT is approximately equal to the LSE estimation with spline interpolator.
6. Improving Channel Estimation in OFDM System Using …
www.ijesi.org 50 | Page
Fig3. MSE v/s SNR plot between all estimation techniques for Dent channel model
4. Number of Subcarriers Comparison
Figure 4 shows the impact of increasing numbers of subcarriers. As the numbers of subcarriers
increases, the mean square error starts decreasing that leads to improvement in channel estimation. The results
are plotted for the DCT based channel estimation
Fig4. MSE v/s Number of Subcarriers plot for DCT based channel estimation technique in OFDM system
V. CONCLUSION
In this paper, improvement in channel estimation in OFDM system using time domain channel
estimation techniques for time correlated Rayleigh fading channel model (Dent channel model) is made. LSE
estimation with spline interpolator and MMSE estimation has poor performance and high complexity as
compared to time domain channel estimation. DFT based channel estimation technique is applied to the LSE
estimated output and reduces the noise in time domain there by increasing the performance and with the use of
Fast algorithms like FFT and IFFT, complexity of the estimation is also reduced. For a non - integer number of
cycles, there arise the problem of spectral leakage and aliasing while using DFT based channel estimation
technique. DCT based channel estimation technique has removed this problem and increases the estimation
performance.
Thus DCT based channel estimation technique shows better performance among all the estimation
techniques. There is one more aspect of increasing the estimation performance by increasing the number of
subcarriers. In this paper, we have realized the improvement of estimation performance by applying it on time
correlated Rayleigh fading channel model i.e. Dent channel model. At high SNR, MMSE with DCT
performance decreases due to high complexity and performance of MMSE with DFT and LSE (spline) with
DFT is approximately equal. The performance can be improved further by the increasing number of subcarriers.
7. Improving Channel Estimation in OFDM System Using …
www.ijesi.org 51 | Page
REFERENCES
[1] Y. Li, L. J. Cimini Jr., and N. R. Sollenberger, “Robust Channel Estimation for OFDM systems with rapid dispersive fading
channels,” IEEE Trans. Comm., Vol.46, no.7, pp.902-915, July 1988.
[2] Srivastava, C. K, Ho, P. H. W. Fung, and S. Sun, “Robust MMSE Channel Estimation in OFDM systems with practical timing
synchronization,” in proc. of wireless communication and networking conference (IEEE WCNC 2004), Vol.2, pp. 711-716,
2004.
[3] B. Gupta, G. Gupta and D. S. Saini, “BER Performance Improvement in OFDM System with ZFE and MMSE Equalizers,” in
proc. of ICNCS 2011, Kanyakumari, India, April 8-10, 2011.
[4] B. Gupta and D.S.Saini, “BER Analysis of Space-Frequency Block Coded MIMO-OFDM Systems Using Different Equalizers in
Quasi-Static Mobile Radio Channel” in proc. of CSNT-11, pp. 520-524, SMVDU, Katra, India, June 2011.
[5] B. Gupta and D.S. Saini, “BER Performance Improvement in Coded-OFDM Systems using Equalization Algorithms,” in proc. of
IEEE ICCRC 2011, vol. 2, pp. 205-210.
[6] P. Dent, G.E. Bottomley and T. Croft, “Jakes Fading Model Revisited”, IEEE Electronic Letters, Vol 29 (13), pp. 1162-1163.
[7] J.J. van der Beek, O. Edfors, M. Sandell, S.K. Wilson,and P.O.Borgesson, “On channel estimation in OFDM systems,” Proc.
VTC’95, pp. 815-819
[8] K. Kwak, S. Lee, J. Kim and D. Hong,” A new DFT-based Channel estimation approach for OFDM with virtual subcarriers by
leakage estimation”, IEEE Transactions on Wireless Communications, Volume: 7, Issue: 6, pp.2004-2008, June 2008
[9] S. Saleem, Q. Islam, “Optimization of LSE and LMMSE Channel Estimation Algorithms based on CIR Samples and Channel
Taps”, IJCSI International Journal of Computer Science Issues, Vol.8, Issue.1, pp. 6-12, Jan 2011.
[10] Y. Baoguo, K. B. Letaief, R. S. Cheng, and C. Zhigang, Windowed DFT based pilot-symbol-aided channel estimation for OFDM
systems in multipath fading channels," in Vehicular Technology ConferenceProceedings, 2000. VTC 2000-Spring Tokyo.
2000IEEE 51st, 2000, pp.1480-1484 vol.2.
[11] Y. H. Yeh and S. G. Chen, “DCT-based channel estimation for OFDM systems”, Communications, 2004 IEEE
InternationalConference, vol. 4, pp.2442-2446, June 2004.
[12] Y. H. Yeh and S. G. Chen, “Efficient channel estimation based on discrete cosine transform,” IEEEICASSP’03, vol. 4, pp. 676-
679.