This document describes modeling mobile radio channels in MATLAB. It introduces concepts for modeling flat fading channels using user-defined m-files. Typical small-scale fading channel models like uncorrelated Rician and Rayleigh fading with Doppler shift are derived. MATLAB code is provided to generate uncorrelated and correlated fading samples. The code also approximates cumulative distribution functions and compares them to analytical distributions. Finally, a Monte Carlo simulation example of digital modulation over a Rician fading channel is presented.
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.
This document simulates and analyzes the Nakagami fading channel using MATLAB. It begins by introducing multipath fading channel models including Rayleigh, Ricean, and Nakagami distributions. It then uses MATLAB to simulate the complex envelope, level crossing rates, and average fade durations of the Nakagami fading channel under various conditions by varying the Nakagami m parameter. The simulations demonstrate how diversity techniques like maximal ratio combining can mitigate fading effects. Increasing the diversity order or Nakagami m parameter results in lower level crossing rates and shorter average fade durations, improving signal quality.
Bit Error Rate Performance of MIMO Spatial Multiplexing with MPSK Modulation ...ijsrd.com
Wireless communication is one of the most effective areas of technology development of our time. Wireless communications today covers a very wide array of applications. In this, we study the performance of general MIMO system, the general V-BLAST architecture with MPSK Modulation in Rayleigh fading channels. Based on bit error rate, we show the performance of the 2x2 schemes with MPSK Modulation in noisy environment. We also show the bit error rate performance of 2x2, 3x3, 4x4 systems with BPSK modulation. We see that the bit error rate performance of 2x2 systems with QPSK modulation gives us the best performance among other schemes analysed here.
A novel and efficient mixed-signal compressed sensing for wide-band cognitive...Polytechnique Montreal
In cognitive radio (CR) networks, unlicensed (cognitive) users can exploit the licensed frequency bands by using spectrum sensing techniques to identify spectrum holes. This paper proposes a distributed compressive spectrum sensing scheme, in which the modulated wide-band converter can apply compressed sensing (CS) directly to analog signals at the sub-Nyquist rate and the central fusion receives signals from multiple CRs and exploits the multiple-measurements-vectors (MMV) subspace pursuit (M-SP) algorithm to jointly reconstruct the spectral support of the wide-band signal. This support is then used to detect whether the licensed bands are occupy or not. Finally, extensive simulation results show the advantages of the proposed scheme. Besides, we also compare the performance of M-SP with M-orthogonal matching pursuit (M-OMP) algorithms.
This document proposes a simultaneous multi-channel reconstruction method for TDS-OFDM systems using distributed compressive sensing. It utilizes an interference-free region within the received pseudorandom noise sequence to reconstruct multiple sparse channels simultaneously, without requiring interference cancellation. A simultaneous CoSaMP algorithm is developed to achieve better channel estimation performance in fast fading channels. Simulation results show the proposed scheme improves performance over conventional solutions.
Singular Value Decomposition: Principles and Applications in Multiple Input M...IJCNCJournal
The authors discuss the importance of using the singular value decomposition (SVD) in computing the capacity of multiple input multiple output (MIMO) and in estimation the channel gain from the transmitter to the receiver. Examples that show how the SVD simplifies computing the MIMO channel capacity are discussed. Numerical results that show what factors determine the performance of using SVD in channel
estimation are also discussed.
Multi carrier equalization by restoration of redundanc y (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.
Capsulization of Existing Space Time TechniquesIJEEE
1) The document discusses space-time coding techniques used in wireless communication systems to improve reliability of data transmission using multiple transmit antennas.
2) It describes space-time block codes (STBC) such as Alamouti codes and orthogonal designs which transmit redundant copies of data across antennas without loss of data rate.
3) It also discusses space-time trellis codes (STTC) which provide coding gain but have higher complexity than STBCs.
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.
This document simulates and analyzes the Nakagami fading channel using MATLAB. It begins by introducing multipath fading channel models including Rayleigh, Ricean, and Nakagami distributions. It then uses MATLAB to simulate the complex envelope, level crossing rates, and average fade durations of the Nakagami fading channel under various conditions by varying the Nakagami m parameter. The simulations demonstrate how diversity techniques like maximal ratio combining can mitigate fading effects. Increasing the diversity order or Nakagami m parameter results in lower level crossing rates and shorter average fade durations, improving signal quality.
Bit Error Rate Performance of MIMO Spatial Multiplexing with MPSK Modulation ...ijsrd.com
Wireless communication is one of the most effective areas of technology development of our time. Wireless communications today covers a very wide array of applications. In this, we study the performance of general MIMO system, the general V-BLAST architecture with MPSK Modulation in Rayleigh fading channels. Based on bit error rate, we show the performance of the 2x2 schemes with MPSK Modulation in noisy environment. We also show the bit error rate performance of 2x2, 3x3, 4x4 systems with BPSK modulation. We see that the bit error rate performance of 2x2 systems with QPSK modulation gives us the best performance among other schemes analysed here.
A novel and efficient mixed-signal compressed sensing for wide-band cognitive...Polytechnique Montreal
In cognitive radio (CR) networks, unlicensed (cognitive) users can exploit the licensed frequency bands by using spectrum sensing techniques to identify spectrum holes. This paper proposes a distributed compressive spectrum sensing scheme, in which the modulated wide-band converter can apply compressed sensing (CS) directly to analog signals at the sub-Nyquist rate and the central fusion receives signals from multiple CRs and exploits the multiple-measurements-vectors (MMV) subspace pursuit (M-SP) algorithm to jointly reconstruct the spectral support of the wide-band signal. This support is then used to detect whether the licensed bands are occupy or not. Finally, extensive simulation results show the advantages of the proposed scheme. Besides, we also compare the performance of M-SP with M-orthogonal matching pursuit (M-OMP) algorithms.
This document proposes a simultaneous multi-channel reconstruction method for TDS-OFDM systems using distributed compressive sensing. It utilizes an interference-free region within the received pseudorandom noise sequence to reconstruct multiple sparse channels simultaneously, without requiring interference cancellation. A simultaneous CoSaMP algorithm is developed to achieve better channel estimation performance in fast fading channels. Simulation results show the proposed scheme improves performance over conventional solutions.
Singular Value Decomposition: Principles and Applications in Multiple Input M...IJCNCJournal
The authors discuss the importance of using the singular value decomposition (SVD) in computing the capacity of multiple input multiple output (MIMO) and in estimation the channel gain from the transmitter to the receiver. Examples that show how the SVD simplifies computing the MIMO channel capacity are discussed. Numerical results that show what factors determine the performance of using SVD in channel
estimation are also discussed.
Multi carrier equalization by restoration of redundanc y (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.
Capsulization of Existing Space Time TechniquesIJEEE
1) The document discusses space-time coding techniques used in wireless communication systems to improve reliability of data transmission using multiple transmit antennas.
2) It describes space-time block codes (STBC) such as Alamouti codes and orthogonal designs which transmit redundant copies of data across antennas without loss of data rate.
3) It also discusses space-time trellis codes (STTC) which provide coding gain but have higher complexity than STBCs.
This paper proposes and analyzes the performance of a selection decode-and-forward cooperative free-space optical communication system using adaptive subcarrier quadrature amplitude modulation. The system employs selective relaying to choose the best intermediate node based on channel state information. Novel expressions are derived for outage probability, spectral efficiency, and bit error rate considering Gamma-Gamma atmospheric turbulence fading. Numerical results show that the proposed adaptive system has improved performance compared to non-adaptive systems and all-active relaying schemes.
1. MIMO (multiple-input multiple-output) communication uses multiple antennas at both the transmitter and receiver to improve performance. It can increase data throughput and link range without additional bandwidth or transmit power.
2. MIMO systems can be modeled as a narrowband channel with n transmit antennas and m receive antennas. The channel is represented by a matrix H. MIMO channels can be decomposed into parallel SISO channels through singular value decomposition to simplify processing.
3. The capacity of MIMO channels is determined through water-filling of the eigenvalues of the channel matrix H. MIMO provides diversity gain through techniques like beamforming and exploiting the diversity-multiplexing tradeoff.
At this present scenario, the demand of the system capacity is very high in wireless network. MIMO
technology is used from the last decade to provide this requirement for wireless network antenna
technology. MIMO channels are mostly used for advanced antenna array technology. But it is most
important to control the error rate with enhanced system capacity in MIMO for present-day progressive
wireless communication. This paper explores the frame error rate with respect to different path gain of
MIMO channel. This work has been done in different fading scenario and produces a comparative analysis
of MIMO on the basis of those fading models in various conditions. Here, it is to be considered that
modulation technique as QPSK to observe these comparative evaluations for different Doppler frequencies.
From the comparative analysis, minimum amount of frame error rate is viewed for Rician distribution at
LOS path Doppler shift of 0 Hz. At last, this work is concluded with a comparative bit error rate study on
the basis of singular parameters at different SNR levels to produce the system performance for uncoded
QPSK modulation.
This document proposes and evaluates a new chaotic communication system called Correlation Delay Shift Keying (CDSK). It summarizes the characteristics and advantages of using chaotic signals for communication. It then describes the CDSK system and compares its bit error rate performance using two different chaos maps (Tent map and a newly proposed Boss map) in additive white Gaussian noise and Rayleigh fading channels. The results show that the Boss map provides better bit error rate performance than the Tent map.
In this paper, three beamforming design are considered for multi user MIMO system. First, transmit
beamformers are fixed and the receive (RX) beamformers are calculated. Transmit beamformer (TX-BF)is
projectedas a null space of appropriate channels. It reduces the interference for each user. Then the receiver
beamformer is determined which maximize the SNR. This beamforming design provides less computation time.
The second case is joint TX and RX beamformer for SNR maximization. In this transmitter and receiver
beamformer are calculated using extended alternating optimization (EAO) algorithm. The third one is joint
transmitter and receiver beamforming for SNR and SINR maximization using EAO algorithm. This algorithm
provides better error performance and sum rate performance. All the design cases are simulated by using
standard multipath channel model. Our simulation results illustrate that compared to the least square design and
zero forcing design, the joint TX and RX beamforming design using EAO algorithm provides faster
beamforming and improved error performance and sum rate.
In this paper, we analyzed a numerical evaluation of the performance of MIMO radio systems in the LTE network environment. Downlink physical layer of the OFDM-MIMO based radio interface is considered for system model and a theoretical analysis of the bit error rate of the two space-time codes (SFBC 2×1 and FSTD 4×2 codes are adopted by the LTE norm as a function of the signal to noise ratio. Analytical expressions are given for transmission over a Rayleigh channel without spatial correlation which is then compared with Monte-Carlo simulations. Further evaluated channel capacity and simulation results show throughput almost reaches to the capacity limit.
Design and Fabrication of a Two Axis Parabolic Solar Dish CollectorIJERA Editor
The work consists of the design of the chain drive system and the fabrication of the two axis parabolic solar dish.
It is a model study of the two axis parabolic dish which worked by the automatic circuit that was developed. Ready
made parabolic solar dish is taken and fabricated. The circular iron ring provides the two axis motion of the dish.
A compound chain drive system was developed for the smooth movement of the dish. An electromechanical
system which tracks the sun on both axes and which is controlled via a programmable logic control (PLC) was
designed and implemented. In this a theoretical study was done. A C program was made which gave the required
result for the graphical representation of the recorded radiation. Programmable Logic Controls (PLC) was used
instead of photo sensors, which are widely used for tracking the sun. The azimuthal angle of the sun from sunrise
to sunset times was calculated for each day of the year at 23.59 Lat & 72.38Longitude in the Northern hemisphere,
the location of the city Mehsana. According to this azimuth angle, the required analog signal was taken from the
PLC analog module and sent to the power window motor, which controlled the position of the panel to ensure that
the rays fall vertically on the panel. After the mechanical control of the system was started, the performance
measurements of the solar panel were carried out. The values obtained from the measurements were compared and
the necessary evaluations were conducted.
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.
Este en un informe en ingles que muestra el impacto que tiene las ondas 5G en la biología humana, se recomienda traducirlo para poder entenderlo en sub totalidad
This document analyzes and compares OFDMA and CDMA/WCDMA systems. It first discusses channel estimation techniques for OFDMA and CDMA, including minimum mean square error (MMSE) and least squares estimation. It then analyzes properties of OFDMA systems, including the effect of total power and cluster size on signal-to-interference plus noise ratio and signal-to-interference ratio. Finally, it compares the downlink capacities of OFDMA and WCDMA systems and proposes a new multiple access technique called OWCFDMA that combines advantages of both. The overall goal is to improve wireless communication system performance by integrating OFDMA and CDMA/WCDMA techniques.
Compressive spectrum sensing using two-stage scheme for cognitive radio netwo...IJECEIAES
The modern applications of communications that use wideband signals suffer the lacking since the resources of this kind of signals are limited especially for fifth generation (5G). The compressive spectrum sensing (COMPSS) techniques address such issues to reuse the detected signals in the networks and applications of 5G. However, the raw techniques of COMPSS have low compression ratio and high computational complexity rather than high level of noise variance. In this paper, a hybrid COMPSS scheme has been developed for both non-cooperative and cooperative cognitive radio networks. The proposed scheme compiles on discrete wavelet transform single resolution (DWT-SR) cascaded with discrete cosine transform (DCT). The first is constructed according to the pyramid algorithm to achieve 50% while the second performed 30% compression ratios. The simulation and analytic results reveal the significant detection performance of the proposed technique is better than that of the raw COMPSS techniques.
1. The document proposes a scheme called Superimposed Spatial Modulation (SSM) that allows for doubling of information conveyed in the spatial position of transmitting antennas.
2. SSM superimposes two independent spatial modulation systems on the same antenna array. Each system transmits different components of orthogonal symbols.
3. This approach increases spectral efficiency over conventional spatial modulation by doubling the size of the possible antenna constellations.
This document summarizes and compares four detection algorithms for spatial modulation with multiple active transmit antennas (MASM): 1) Maximum likelihood (ML) detection, which performs an exhaustive search over all possible symbol vectors; 2) A decorrelator-based suboptimal detection method; 3) An ordered block minimum mean square error (OB-MMSE) detection method; 4) A proposed simplified ML detection method based on symbol cancellation and multi-level subset searching. Through simulations, the proposed detector is found to perform the same as ML detection down to bit error rates of 10-6, with lower complexity than ML detection and OB-MMSE for most configurations.
An improved dft based channel estimationsakru naik
This document proposes an improved DFT-based channel estimation method for MIMO-OFDM systems. The conventional DFT method causes energy leakage in non-sample-spaced multipath channels. The improved method extends the LS estimate using symmetry, calculates the changing rate of leakage energy, and selects useful paths based on this rate to reduce leakage energy. Simulation results show the improved method reduces leakage energy more efficiently and provides better channel estimation performance than LS and conventional DFT algorithms.
This document proposes applying Euclidean Distance Antenna Selection (EDAS) to Multiple Active Spatial Modulation (MASM) to improve its performance. It describes MASM and introduces a new method called Euclidean Distance Antenna Group Selection (EDAGS) that selects antenna groups to maximize the Euclidean distance between symbols. Due to high complexity, it also proposes applying the ideas of EDAS and capacity-optimized antenna selection (COAS) to MASM by selecting antennas first and then forming groups from them. The remainder of the paper will analyze the complexity of the methods, provide simulation results, and give concluding remarks.
EVALUATION OF MIMO SYSTEM CAPACITY OVER RAYLEIGH FADING CHANNELIJCSES Journal
High transmission data rate, spectral efficiency and reliability are essential for future wireless
communications systems. MIMO (multi-input multi-output) diversity technique is a band width efficient
system achieving high data transmission which eventually establishing a high capacity communication
system. Without needing to increase the transmitted power or the channel bandwidth, gain in capacity can
be considerably improved by varying the number of antennas on both sides. Correlated and uncorrelated
channels MIMO system was considered in this paper for different number of antennas and different SNR
over Rayleigh fading channel. At the transmitter both CSI(channel state information) technique and Water
filling power allocation principle was also considered in this paper.
Localized Algorithm for Channel Assignment in Cognitive Radio NetworksIJERA Editor
Cognitive Radio has been emerged as a revolutionary solution to migrate the current shortage of spectrum
allocation in wireless networks. In this paper, an improved localized channel allocation algorithm based on
channel weight is proposed. A factor of channel stability is introduced based on link environment, which
efficiently assigns the best channels to the links. Based on the framework, a conflict resolution strategy is used to
make the scheme adaptable to different network conditions. Calculations indicate that this algorithm can reduce
the conflicts, increase the delivery rate and link assignment rate compared with the basic channel assignment
algorithm.
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.
Interferogram Filtering Using Gaussians Scale Mixtures in Steerable Wavelet D...CSCJournals
An interferogram filtering is presented in this paper. The main concern of the proposed scheme is to lower the residues count mean while preserving the location and jump height of the lines of phase discontinuity. The proposed method is based on a statistical model of the coefficients of multi-scale oriented basis. Neighborhoods of coefficients at adjacent positions and scales are modeled as the product of two independent random variables: a Gaussian vector and a hidden positive scalar multiplier. Under this model, the Bayesian least squares estimate of each coefficient reduces to a weighted average of the local linear estimates over all possible values of the hidden multiplier variable. The performance of this method substantially has the advantages of reducing number of residuals without affecting line of height discontinuity.
The document compares the performance of a Root Raised Cosine matched filter implemented using hybrid-logarithmic arithmetic versus standard binary and floating point arithmetic. Simulations showed that the hybrid logarithmic structure offered superior performance to fixed point solutions while having significantly reduced complexity compared to floating point equivalents. The use of hybrid logarithmic arithmetic also has the potential to reduce power consumption, latency, and hardware complexity for mobile applications.
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.
Simulation model for a frequency selective land mobile satellite communicatio...Alexander Decker
The document describes a simulation model for a frequency-selective land mobile satellite communication channel. It develops a three-state channel model consisting of Rayleigh, Rician, and Loo fading processes to characterize different propagation conditions. The model accounts for effects such as multipath fading, shadowing, and line-of-sight components. It generates frequency-selective fading for each state using tapped delay line techniques. The model allows evaluating performance of land mobile satellite systems under various propagation conditions.
This paper proposes and analyzes the performance of a selection decode-and-forward cooperative free-space optical communication system using adaptive subcarrier quadrature amplitude modulation. The system employs selective relaying to choose the best intermediate node based on channel state information. Novel expressions are derived for outage probability, spectral efficiency, and bit error rate considering Gamma-Gamma atmospheric turbulence fading. Numerical results show that the proposed adaptive system has improved performance compared to non-adaptive systems and all-active relaying schemes.
1. MIMO (multiple-input multiple-output) communication uses multiple antennas at both the transmitter and receiver to improve performance. It can increase data throughput and link range without additional bandwidth or transmit power.
2. MIMO systems can be modeled as a narrowband channel with n transmit antennas and m receive antennas. The channel is represented by a matrix H. MIMO channels can be decomposed into parallel SISO channels through singular value decomposition to simplify processing.
3. The capacity of MIMO channels is determined through water-filling of the eigenvalues of the channel matrix H. MIMO provides diversity gain through techniques like beamforming and exploiting the diversity-multiplexing tradeoff.
At this present scenario, the demand of the system capacity is very high in wireless network. MIMO
technology is used from the last decade to provide this requirement for wireless network antenna
technology. MIMO channels are mostly used for advanced antenna array technology. But it is most
important to control the error rate with enhanced system capacity in MIMO for present-day progressive
wireless communication. This paper explores the frame error rate with respect to different path gain of
MIMO channel. This work has been done in different fading scenario and produces a comparative analysis
of MIMO on the basis of those fading models in various conditions. Here, it is to be considered that
modulation technique as QPSK to observe these comparative evaluations for different Doppler frequencies.
From the comparative analysis, minimum amount of frame error rate is viewed for Rician distribution at
LOS path Doppler shift of 0 Hz. At last, this work is concluded with a comparative bit error rate study on
the basis of singular parameters at different SNR levels to produce the system performance for uncoded
QPSK modulation.
This document proposes and evaluates a new chaotic communication system called Correlation Delay Shift Keying (CDSK). It summarizes the characteristics and advantages of using chaotic signals for communication. It then describes the CDSK system and compares its bit error rate performance using two different chaos maps (Tent map and a newly proposed Boss map) in additive white Gaussian noise and Rayleigh fading channels. The results show that the Boss map provides better bit error rate performance than the Tent map.
In this paper, three beamforming design are considered for multi user MIMO system. First, transmit
beamformers are fixed and the receive (RX) beamformers are calculated. Transmit beamformer (TX-BF)is
projectedas a null space of appropriate channels. It reduces the interference for each user. Then the receiver
beamformer is determined which maximize the SNR. This beamforming design provides less computation time.
The second case is joint TX and RX beamformer for SNR maximization. In this transmitter and receiver
beamformer are calculated using extended alternating optimization (EAO) algorithm. The third one is joint
transmitter and receiver beamforming for SNR and SINR maximization using EAO algorithm. This algorithm
provides better error performance and sum rate performance. All the design cases are simulated by using
standard multipath channel model. Our simulation results illustrate that compared to the least square design and
zero forcing design, the joint TX and RX beamforming design using EAO algorithm provides faster
beamforming and improved error performance and sum rate.
In this paper, we analyzed a numerical evaluation of the performance of MIMO radio systems in the LTE network environment. Downlink physical layer of the OFDM-MIMO based radio interface is considered for system model and a theoretical analysis of the bit error rate of the two space-time codes (SFBC 2×1 and FSTD 4×2 codes are adopted by the LTE norm as a function of the signal to noise ratio. Analytical expressions are given for transmission over a Rayleigh channel without spatial correlation which is then compared with Monte-Carlo simulations. Further evaluated channel capacity and simulation results show throughput almost reaches to the capacity limit.
Design and Fabrication of a Two Axis Parabolic Solar Dish CollectorIJERA Editor
The work consists of the design of the chain drive system and the fabrication of the two axis parabolic solar dish.
It is a model study of the two axis parabolic dish which worked by the automatic circuit that was developed. Ready
made parabolic solar dish is taken and fabricated. The circular iron ring provides the two axis motion of the dish.
A compound chain drive system was developed for the smooth movement of the dish. An electromechanical
system which tracks the sun on both axes and which is controlled via a programmable logic control (PLC) was
designed and implemented. In this a theoretical study was done. A C program was made which gave the required
result for the graphical representation of the recorded radiation. Programmable Logic Controls (PLC) was used
instead of photo sensors, which are widely used for tracking the sun. The azimuthal angle of the sun from sunrise
to sunset times was calculated for each day of the year at 23.59 Lat & 72.38Longitude in the Northern hemisphere,
the location of the city Mehsana. According to this azimuth angle, the required analog signal was taken from the
PLC analog module and sent to the power window motor, which controlled the position of the panel to ensure that
the rays fall vertically on the panel. After the mechanical control of the system was started, the performance
measurements of the solar panel were carried out. The values obtained from the measurements were compared and
the necessary evaluations were conducted.
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.
Este en un informe en ingles que muestra el impacto que tiene las ondas 5G en la biología humana, se recomienda traducirlo para poder entenderlo en sub totalidad
This document analyzes and compares OFDMA and CDMA/WCDMA systems. It first discusses channel estimation techniques for OFDMA and CDMA, including minimum mean square error (MMSE) and least squares estimation. It then analyzes properties of OFDMA systems, including the effect of total power and cluster size on signal-to-interference plus noise ratio and signal-to-interference ratio. Finally, it compares the downlink capacities of OFDMA and WCDMA systems and proposes a new multiple access technique called OWCFDMA that combines advantages of both. The overall goal is to improve wireless communication system performance by integrating OFDMA and CDMA/WCDMA techniques.
Compressive spectrum sensing using two-stage scheme for cognitive radio netwo...IJECEIAES
The modern applications of communications that use wideband signals suffer the lacking since the resources of this kind of signals are limited especially for fifth generation (5G). The compressive spectrum sensing (COMPSS) techniques address such issues to reuse the detected signals in the networks and applications of 5G. However, the raw techniques of COMPSS have low compression ratio and high computational complexity rather than high level of noise variance. In this paper, a hybrid COMPSS scheme has been developed for both non-cooperative and cooperative cognitive radio networks. The proposed scheme compiles on discrete wavelet transform single resolution (DWT-SR) cascaded with discrete cosine transform (DCT). The first is constructed according to the pyramid algorithm to achieve 50% while the second performed 30% compression ratios. The simulation and analytic results reveal the significant detection performance of the proposed technique is better than that of the raw COMPSS techniques.
1. The document proposes a scheme called Superimposed Spatial Modulation (SSM) that allows for doubling of information conveyed in the spatial position of transmitting antennas.
2. SSM superimposes two independent spatial modulation systems on the same antenna array. Each system transmits different components of orthogonal symbols.
3. This approach increases spectral efficiency over conventional spatial modulation by doubling the size of the possible antenna constellations.
This document summarizes and compares four detection algorithms for spatial modulation with multiple active transmit antennas (MASM): 1) Maximum likelihood (ML) detection, which performs an exhaustive search over all possible symbol vectors; 2) A decorrelator-based suboptimal detection method; 3) An ordered block minimum mean square error (OB-MMSE) detection method; 4) A proposed simplified ML detection method based on symbol cancellation and multi-level subset searching. Through simulations, the proposed detector is found to perform the same as ML detection down to bit error rates of 10-6, with lower complexity than ML detection and OB-MMSE for most configurations.
An improved dft based channel estimationsakru naik
This document proposes an improved DFT-based channel estimation method for MIMO-OFDM systems. The conventional DFT method causes energy leakage in non-sample-spaced multipath channels. The improved method extends the LS estimate using symmetry, calculates the changing rate of leakage energy, and selects useful paths based on this rate to reduce leakage energy. Simulation results show the improved method reduces leakage energy more efficiently and provides better channel estimation performance than LS and conventional DFT algorithms.
This document proposes applying Euclidean Distance Antenna Selection (EDAS) to Multiple Active Spatial Modulation (MASM) to improve its performance. It describes MASM and introduces a new method called Euclidean Distance Antenna Group Selection (EDAGS) that selects antenna groups to maximize the Euclidean distance between symbols. Due to high complexity, it also proposes applying the ideas of EDAS and capacity-optimized antenna selection (COAS) to MASM by selecting antennas first and then forming groups from them. The remainder of the paper will analyze the complexity of the methods, provide simulation results, and give concluding remarks.
EVALUATION OF MIMO SYSTEM CAPACITY OVER RAYLEIGH FADING CHANNELIJCSES Journal
High transmission data rate, spectral efficiency and reliability are essential for future wireless
communications systems. MIMO (multi-input multi-output) diversity technique is a band width efficient
system achieving high data transmission which eventually establishing a high capacity communication
system. Without needing to increase the transmitted power or the channel bandwidth, gain in capacity can
be considerably improved by varying the number of antennas on both sides. Correlated and uncorrelated
channels MIMO system was considered in this paper for different number of antennas and different SNR
over Rayleigh fading channel. At the transmitter both CSI(channel state information) technique and Water
filling power allocation principle was also considered in this paper.
Localized Algorithm for Channel Assignment in Cognitive Radio NetworksIJERA Editor
Cognitive Radio has been emerged as a revolutionary solution to migrate the current shortage of spectrum
allocation in wireless networks. In this paper, an improved localized channel allocation algorithm based on
channel weight is proposed. A factor of channel stability is introduced based on link environment, which
efficiently assigns the best channels to the links. Based on the framework, a conflict resolution strategy is used to
make the scheme adaptable to different network conditions. Calculations indicate that this algorithm can reduce
the conflicts, increase the delivery rate and link assignment rate compared with the basic channel assignment
algorithm.
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.
Interferogram Filtering Using Gaussians Scale Mixtures in Steerable Wavelet D...CSCJournals
An interferogram filtering is presented in this paper. The main concern of the proposed scheme is to lower the residues count mean while preserving the location and jump height of the lines of phase discontinuity. The proposed method is based on a statistical model of the coefficients of multi-scale oriented basis. Neighborhoods of coefficients at adjacent positions and scales are modeled as the product of two independent random variables: a Gaussian vector and a hidden positive scalar multiplier. Under this model, the Bayesian least squares estimate of each coefficient reduces to a weighted average of the local linear estimates over all possible values of the hidden multiplier variable. The performance of this method substantially has the advantages of reducing number of residuals without affecting line of height discontinuity.
The document compares the performance of a Root Raised Cosine matched filter implemented using hybrid-logarithmic arithmetic versus standard binary and floating point arithmetic. Simulations showed that the hybrid logarithmic structure offered superior performance to fixed point solutions while having significantly reduced complexity compared to floating point equivalents. The use of hybrid logarithmic arithmetic also has the potential to reduce power consumption, latency, and hardware complexity for mobile applications.
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.
Simulation model for a frequency selective land mobile satellite communicatio...Alexander Decker
The document describes a simulation model for a frequency-selective land mobile satellite communication channel. It develops a three-state channel model consisting of Rayleigh, Rician, and Loo fading processes to characterize different propagation conditions. The model accounts for effects such as multipath fading, shadowing, and line-of-sight components. It generates frequency-selective fading for each state using tapped delay line techniques. The model allows evaluating performance of land mobile satellite systems under various propagation conditions.
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.
This document discusses fading models for radio communications. It divides fading into three scales: fast fading caused by constructive/destructive interference from nearby objects; slow fading ("shadowing") from larger structures; and path loss over distance. It describes several statistical distributions used to model small-scale fading, including Rayleigh, Ricean, Nakagami, and Weibull. It also examines slow fading and correlations between locations. The goal is to understand fading effects and design communications to overcome noise while minimizing interference.
Performance of cognitive radio networks with maximal ratio combining over cor...Polytechnique Montreal
This document analyzes the performance of cognitive radio networks using maximal ratio combining over correlated Rayleigh fading channels. It presents a simple analytical method to derive closed-form expressions for the probabilities of detection and false alarm. The key findings are:
1) The detection probability is a monotonically increasing function of the number of antennas, as more antennas provides more diversity gain.
2) Antenna correlation degrades the sensing performance compared to independent antennas. Higher correlation results in lower detection probability.
3) Complementary receiver operating characteristic curves illustrate that both higher signal-to-noise ratio and lower antenna correlation improve detection performance by increasing the detection probability and decreasing the probability of miss at a given false alarm probability.
SαS noise suppression for OFDM wireless communication in rayleight channel IJECEIAES
Orthogonal frequency division multiplexing (OFDM) is a form of multicarrier transmission technique widely used in the modern wireless network to achieve high-speed data transmission with good spectral efficiency. However, in impulsive noise environement BER performances of these systems, originally designed for a Gaussian noise model, are much degraded. In this paper, a new symmetric-alpha-stable (SαS) noise suppression technique based conjointly on adaptive modulation, convolutional coding (AMC) and Recursive Least Square (RLS) filtering is presented. The proposed scheme is applied on OFDM system in Rayleigh fading channel. The transmissions are analyzed under different combinations of digital modulation schemes (BPSK, QPSK, 16-QAM, 64-QAM) and convolutional code rates (1/2, 2/3, 3/4). Simulation results show that our proposed hybrid technique provides effective impulsive noise cancelation in OFDM system and exhibits better BER performance.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance Analysis of Rician Fading Channels using Nonlinear Modulation Met...IOSR Journals
This document discusses performance analysis of Rician fading channels using non-linear modulation methods with memory schemes in Simulink. It begins with an introduction to different types of channel fading including log-normal shadowing, Rayleigh fading, Ricean fading, Nakagami fading, and Suzuki fading. It then reviews the wide sense stationary uncorrelated scattering (WSSUS) model and discusses delay spread and correlation coefficient in wireless channels. The goal of the paper is to implement and analyze the bit error rate of Ricean fading channels using non-linear modulation and memory schemes in Simulink.
Iterative Soft Decision Based Complex K-best MIMO DecoderCSCJournals
This paper presents an iterative soft decision based complex multiple input multiple output (MIMO) decoding algorithm, which reduces the complexity of Maximum Likelihood (ML) detector. We develop a novel iterative complex K-best decoder exploiting the techniques of lattice reduction for 8×8 MIMO. Besides list size, a new adjustable variable has been introduced in order to control the on-demand child expansion. Following this method, we obtain 6.9 to 8.0 dB improvement over real domain K-best decoder and 1.4 to 2.5 dB better performance compared to iterative conventional complex decoder for 4th iteration and 64-QAM modulation scheme. We also demonstrate the significance of new parameter on bit error rate. The proposed decoder not only increases the performance, but also reduces the computational complexity to a certain level.
Iterative Soft Decision Based Complex K-best MIMO DecoderCSCJournals
This paper presents an iterative soft decision based complex multiple input multiple output (MIMO) decoding algorithm, which reduces the complexity of Maximum Likelihood (ML) detector. We develop a novel iterative complex K-best decoder exploiting the techniques of lattice reduction for 8×8 MIMO. Besides list size, a new adjustable variable has been introduced in order to control the on-demand child expansion. Following this method, we obtain 6.9 to 8.0 dB improvement over real domain K-best decoder and 1.4 to 2.5 dB better performance compared to iterative conventional complex decoder for 4th iteration and 64-QAM modulation scheme. We also demonstrate the significance of new parameter on bit error rate. The proposed decoder not only increases the performance, but also reduces the computational complexity to a certain level.
Improvement of Fading Channel Modeling Performance for Wireless Channel IJECEIAES
Fading channel modeling is generally defined as the variation of the attenuation of a signal with various variables. Time, geographical position, and radio frequency which is included. Fading is often modeled as a random process. Thus, a fading channel is a communication channel that experiences fading. In this paper, the proposed system presents a new design and simulate a wireless channel using Rayleigh channels. Rayleigh channels using two approaches (flat and frequency-selective fading channels) in order to calculate some path space loss efforts and analysis the performance of different wireless fading channel modeling. The results show that the bite error rate (BER) performance is dramatically improved in the value of signal to noise ratio (SNR) is equal to 45dB. Finally, the experimental results show that the proposed method enhances the performance of fading channel modeling by reducing the error of BER when the SNR is reduced also. Moreover, the more accurate model is Rayleigh model which can be considered for developing fading channel model.
On the Performance Analysis of Composite Multipath/Shadowing (Weibull-Log Nor...IJEEE
Composite multipath/shadowing fading environments are frequently encountered in different mobile realistic scenarios. These channels are generally modeled differentComposite multipath/shadowing fading. In this paper wepresent the performance analysis of composite (Weibull-Lognormal shadowed) fading. We adopt efficient toolproposed by Holtzman to approximate composite (Weibull-Lognormal shadowed) fading. The performance measures offading communication systems such as Probability densityfunction (PDF) of Signal to Noise ratio (SNR), Amount offading (AF), Outage probability (Pout) and ChannelCapacity(C/B) will be calculated. Graphical results will bepresented for different signals and fading parameters. Thedifferent expressions that will be provided are of greatimportance in assessing the performance of communicationsystems in composite channels.
This document proposes a discrete wavelet transform (DWT)-based channel estimation method for MIMO-OFDM systems. It describes the transmitter and receiver structures of a wavelet-based OFDM system with multiple antennas. At the transmitter, data is modulated using inverse DWT and transmitted over frequency-selective channels. At the receiver, received signals are processed using DWT to estimate the channel. Least squares and minimum mean squared error estimation techniques are discussed. Simulation results show the DWT-based system achieves better bit error rate performance than conventional FFT-based OFDM.
Design of Low-Pass Digital Differentiators Based on B-splinesCSCJournals
This paper describes a new method for designing low-pass differentiators that could be widely suitable for low-frequency signals with different sampling rates. The method is based on the differential property of convolution and the derivatives of B-spline bias functions. The first order differentiator is just constructed by the first derivative of the B-spline of degree 5 or 4. A high (>2) order low-pass differentiator is constructed by cascading two low order differentiators, of which the coefficients are obtained from the nth derivative of a B-spline of degree n+2 expanded by factor a. In this paper, the properties of the proposed differentiators were presented. In addition, we gave the examples of designing the first to sixth order differentiators, and several simulations, including the effects of the factor a on the results and the anti-noise capability of the proposed differentiators. These properties analysis and simulations indicate that the proposed differentiator can be applied to a wide range of low-frequency signals, and the trade-off between noise- reduction and signal preservation can be made by selecting the maximum allowable value of a.
This document discusses a proposed architecture for a higher Nyquist-range digital-to-analog converter (DAC) that employs sinusoidal interpolation.
[1] Conventional DACs operate within the Nyquist range, but the proposed architecture aims to utilize higher Nyquist ranges by approximating an oscillating signal from an RF DAC concept using sinusoidal interpolation in the time domain.
[2] The proposed architecture quantizes both the input signal and pulse amplitude modulation waveform and combines them digitally, replacing analog oscillatory circuits with a digital data stream. This reduces analog complexity compared to existing techniques.
[3] Simulation results and theoretical analysis are presented to support that the proposed architecture can provide similar performance
Narrowband Spectrum Sensing for Different Fading Channels for Cognitive Radio...IJMERJOURNAL
Abstract: Nowadays the demand of applications of wireless communication has increased rapidly which causes the scarcity of radio spectrum. To empower future wireless communication services, the radio spectrum management is a very important factor. Cognitiveradio is a promising technology which provides an innovative way to improve utilization efficiency of available electromagnetic spectrum by sensing spectrum and shares it without harmful interference to other users. Narrowband spectrum sensing is the technique where the bandwidth of active primary transmitter in the vicinity of cognitive radio is less than the coherence bandwidth of channel. Fading is one of the greatest impairment of narrowband spectrum sensing. It is deflection of the attenuation. It influences a signal over certain propagation media.A communication channel that experiences fading isknown as fading channel. The effects of fading can be reduced by several fading models. In this paper, performanceanalysis of several realistic fading models on narrowband channel using energy detection method is employed. Finally, performance comparison of various fading models is guaranteed through simulation.
Performance of Wideband Mobile Channel with Perfect Synchronism BPSK vs QPSK ...Editor Jacotech
Direct-sequence code-division multiple access (DS-CDMA) is
currently the subject of much research as it is a promising
multiple access capability for third and fourth generations
mobile communication systems. The synchronous DS-CDMA
system is well known for eliminating the effects of multiple
access interference (MAI) which limits the capacity and
degrades the BER performance of the system. In this paper,
we investigate the bit error rate (BER) performance of a
synchronous DS-CDMA system over a wideband mobile
radio channel. The BER performance is affected by the
difference in path length ΔL and the number of arriving
signals N. Furthermore, the effect of these parameters is
examined on the synchronous DS-CDMA system for different
users’ number as well as different processing gain Gp. In this
environment and under the above conditions the performances
of the BPSK (Binary Phase Shift Keying) and the QPSK
(Quadrature Phase Shift Keying) modulations are compared.
The promising simulation results showed the possibility of
applying this system to the wideband mobile radio channel.
This document proposes using a hybrid model and structured sparsity for under-determined convolutive audio source separation. It presents a mathematical model that combines a convex cost function with sparse regularization terms. A hybrid model is introduced using a union of two Gabor frames, each adapted to a different "morphological layer" of the signal. Structured sparsity is incorporated using a windowed group lasso operator to better exploit time-frequency structure. Experiments on speech and music mixtures show improved source separation performance compared to baseline methods, confirming the benefits of the proposed hybrid and structured sparsity approaches.
Bounds on the Achievable Rates of Faded Dirty Paper Channel IJCNCJournal
Bounds on the achievable rate of a Gaussian channel in the case that the transmitter knows the
interference signal but not its fading coefficients are given. We generalize the analysis which were studied
in [1] and [4] so that their results are special cases of our analysis. We enforce our bounds by simulations
in which many numerical examples are drawn and investigated under different cases.
Fixed Point Realization of Iterative LR-Aided Soft MIMO Decoding AlgorithmCSCJournals
Multiple-input multiple-output (MIMO) systems have been widely acclaimed in order to provide high data rates. Recently Lattice Reduction (LR) aided detectors have been proposed to achieve near Maximum Likelihood (ML) performance with low complexity. In this paper, we develop the fixed point design of an iterative soft decision based LR-aided K-best decoder, which reduces the complexity of existing sphere decoder. A simulation based word-length optimization is presented for physical implementation of the K-best decoder. Simulations show that the fixed point result of 16 bit precision can keep bit error rate (BER) degradation within 0.3 dB for 8×8 MIMO systems with different modulation schemes.
Similar to Mobile radio chaneel matlab kostov (20)
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Building Production Ready Search Pipelines with Spark and MilvusZilliz
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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
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- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
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Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
Monitoring and observability aren’t traditionally found in software curriculums and many of us cobble this knowledge together from whatever vendor or ecosystem we were first introduced to and whatever is a part of your current company’s observability stack.
While the dev and ops silo continues to crumble….many organizations still relegate monitoring & observability as the purview of ops, infra and SRE teams. This is a mistake - achieving a highly observable system requires collaboration up and down the stack.
I, a former op, would like to extend an invitation to all application developers to join the observability party will share these foundational concepts to build on:
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
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We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/building-and-scaling-ai-applications-with-the-nx-ai-manager-a-presentation-from-network-optix/
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In this presentation, van Emden covers the basics of scaling edge AI solutions using the Nx tool kit. He emphasizes the process of developing AI models and deploying them globally. He also showcases the conversion of AI models and the creation of effective edge AI pipelines, with a focus on pre-processing, model conversion, selecting the appropriate inference engine for the target hardware and post-processing.
van Emden shows how Nx can simplify the developer’s life and facilitate a rapid transition from concept to production-ready applications.He provides valuable insights into developing scalable and efficient edge AI solutions, with a strong focus on practical implementation.
Maruthi Prithivirajan, Head of ASEAN & IN Solution Architecture, Neo4j
Get an inside look at the latest Neo4j innovations that enable relationship-driven intelligence at scale. Learn more about the newest cloud integrations and product enhancements that make Neo4j an essential choice for developers building apps with interconnected data and generative AI.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
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In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
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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.
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Mobile radio chaneel matlab kostov
1. 12 N. KOSTOV, MOBILE RADIO CHANNELS MODELING IN MATLAB
Mobile Radio Channels Modeling in MATLAB
Nikolay KOSTOV
Department of Radio Engineering, Technical University of Varna, Student 1, 9010 Varna, Bulgaria
n_kostov@mail.bg
Abstract. In this paper, a MATLAB based approach for
mobile radio channels modeling is presented. Specifically,
the paper introduces the basic concepts for modeling flat
fading channels in MATLAB by means of user-defined m-
files. Typical small-scale fading channel models are deri-
ved such as uncorrelated Rician fading channel and Ray-
leigh fading channel with Doppler shift. Further, simple
and useful MATLAB constructions for approximation of
cumulative distribution functions (CDFs) and probability
density functions (PDFs) are also given. Finally, a MAT-
LAB based Monte Carlo simulation example is presented,
which comprises performance estimation of phase shift
keying (PSK) signaling over a Rician fading channel.
Keywords
MATLAB, fading channels, distribution, simulation.
1. Introduction
In digital communication theory the most frequently
assumed model for a transmission channel is the additive
white Gaussian noise (AWGN) channel. However, for ma-
ny communication systems the AWGN channel is a poor
model, and one must resort to more precise and complica-
ted channel models. One basic type of non-Gaussian chan-
nel, which frequently occurs in practice, is the fading chan-
nel. A typical example of such a fading channel is the mo-
bile radio channel, where the small antennas of portable
units pick up multipath reflections. Thus, the mobile chan-
nel exhibits a time varying behavior in the received signal
energy, which is called fading.
Using MATLAB for digital communication systems
simulation one has the advantage of exploiting the power-
ful features of its Communications Toolbox along with
a nice programming language. However, the Communica-
tions Toolbox of MATLAB suffers from absence of proper
mobile channel models. The only available channel model
in the current Communications Toolbox 2.1 is the awgn m-
file, which is appropriate for an AWGN channel simula-
tion. So, the users of MATLAB should build appropriate
channels (i.e., m-files) in their own to reach the desired
simulation model.
The paper is organized as follows. In Section 2, a
brief introduction to fading channels is given. The basic
concepts for modeling flat fading channels in MATLAB
are presented in Section 3. In this section, example m-files
are proposed to model different types of flat fading chan-
nels. In Section 4, a MATLAB based Monte Carlo simula-
tion example is presented, which describes the basic con-
cepts of digital modulations performance estimation over
fading channels. Finally, the concluding remarks are given
in Section 5.
2. The Mobile Radio Channel
The mobile radio channel is characterized by two
types of fading effects: large-scale fading and small scale
fading [1], [2]. Large-scale fading is the slow variation of
the mean (distant-dependent) signal power over time. This
depends on the presence of obstacles in the signal path and
on the position of the mobile unit. The large-scale fading is
assumed to be a slow process and is commonly modeled as
having lognormal statistics. Small-scale fading is also cal-
led Rayleigh or Rician fading because if a large number of
reflective paths is encountered the received signal envelope
is described by a Rayleigh or a Rician probability density
function (PDF) [3]. The small-scale fading under conside-
ration is assumed to be a flat fading (i.e., there is no inter-
symbol interference). It is also assumed that the fading le-
vel remains approximately constant for (at least) one sig-
naling interval. With this model of fading channel the main
difference with respect to an AWGN channel resides in the
fact that fading amplitudes are now Rayleigh- or Rician-
distributed random variables, whose values affect the signal
amplitude (and, hence, the power) of the received signal.
The fading amplitudes can be modeled by a Rician or
a Rayleigh distribution, depending on the presence or ab-
sence of specular signal component. Fading is Rayleigh if
the multiple reflective paths are large in number and there
is no dominant line-of-sight (LOS) propagation path. If
there is also a dominant LOS path, then the fading is Ri-
cian-distributed. The fading amplitude ri at the ith time in-
stant can be represented as
22
)( iii yxr ++= β , (1)
where β is the amplitude of the specular component and xi,
yi are samples of zero-mean stationary Gaussian random
processes each with variance σ0
2
. The ratio of specular to
defuse energy defines the so-called Rician K-factor, which
is given by
2. RADIOENGINEERING, VOL. 12, NO. 4, DECEMBER 2003 13
2
0
2
2/ σβ=K . (2)
The best- and worst-case Rician fading channels associated
with K-factors of K = ∞ and K = 0 are the Gaussian and
Rayleigh channels with strong LOS and no LOS path, res-
pectively. So, the Rayleigh fading channel can be conside-
red as a special case of a Rician fading channel with K = 0.
The Rician PDF is given by [3]
[ ] 02/)(exp)( 2
0
0
2
0
22
2
0
≥
+−= r
r
Ir
r
rfRice
σ
β
σβ
σ
, (3)
where I0[.] is the zero-order modified Bessel function of the
first kind. Now, if there is no dominant propagation path,
K = 0 and I0[.] = 1 yielding the worst-case Rayleigh PDF
[ ] 02/exp)( 2
0
2
2
0
≥−= rr
r
rfRayleigh σ
σ
. (4)
The Rician cumulative distribution function (CDF) takes
the shape of [3]
( ) ∑
∞
=
⋅
−−=
0
2
0
exp1)(
m
m
m
Rice
r
I
r
rC
σ
ββ
γ , (5)
where γ = (K + r2
/ 2σ0
2
). Clearly, this formula is more dif-
ficult to evaluate than the PDF of (3) due to the summation
of an infinite number of terms. However, in practical terms
it is sufficient to increase m to the value, where the last
terms contribution becomes less than 0.1 percent.
0 200 400 600 800 1000
-20
-15
-10
-5
0
5
Samples
Amplitude/RMS(dB)
Fig. 1. A typical Rician fading envelope for K = 5 dB.
Having described the main fading statistics let us consider
the effects of the Doppler frequency shift. Doppler shift
from the carrier frequency fc occurs when the distance bet-
ween the mobile receiver and the transmitter is changing.
The magnitude of the Doppler frequency shift fm is determi-
ned by
c
fv
f c
m = , (6)
where ν is the mobile station velocity and c = 3⋅108
m/s is
the speed of light. The Doppler frequency fm is often called
fading bandwidth or fading fate of the channel. The rela-
tionship between fm and the coherence time Tm of the chan-
nel (i.e., the time over which the channel’s response to a
sinusoid is essentially invariant) is given by [1]
m
m
f
T
5.0
≈ . (7)
The Doppler power spectral density S(f) of the mobile
channel is often expressed as [4], [5]
2
)/(1
1
)(
mm fff
fS
−
=
π
. (8)
The above equality holds for frequency shifts of f in the
range ±fm about the carrier frequency fc.
Some important notes are in order here. First, the pri-
mary factor, which affects the performance of digital com-
munication systems in a mobile environment, is the small-
scale fading. So, we will consider Rayleigh and Rician fa-
ding channels from now on. Second, uncorrelated Ray-
leigh- or Rician-distributed fading sequences can be obtai-
ned directly by exploiting (1). Third, correlated fading se-
quences can be obtained by means of “colored” Gaussian
noise processes. A well-known approach is the so-called
sum-of-sinusoids method in which a “colored” Gaussian
noise is approximated by a finite sum of weighted and pro-
perly designed sinusoids [5]-[8]. In this paper we opt on the
modified sum-of-sinusoids method as described in [8], be-
cause of its improved statistical properties and simple
software realization.
3. Fading Generation in MATLAB
Let us first consider the generation of uncorrelated
Rician-distributed fading sequences in MATLAB. The
mean-squared value of the Rician distribution is known to
be 2σ0
2
( K + 1), where σ0
2
is the variance of the component
Gaussian noise processes in (1). Further, it is often required
a Rician distribution with unit mean-squared value, i.e.,
E{r2
} = 1, so that the signal power and the signal-to-noise
ratio (SNR) coincide. In order to meet the requirement
E{r2
} = 1, the equation (1) can be written in the form
)1(2
)2( 22
+
++
=
K
yKx
r ii
i
, (9)
where now xi, yi are samples of zero-mean stationary Gaus-
sian random processes each with variance σ0
2
= 1. So, the
desired Rician fading sequences can be generated accor-
ding to (9) by using the MATLAB random number genera-
tor randn, which produces normally distributed random
numbers. The following MATLAB m-file rice_fading
does the task.
function r = rice_fading(Kdb, N, Mi)
K = 10^(Kdb/10); const = 1/(2*(K+1));
x = randn(1,N); y = randn(1,N);
r = sqrt(const*((x + sqrt(2*K)).^2 + y.^2));
rt = zeros(1,Mi*length(r)); ki = 1;
3. 14 N. KOSTOV, MOBILE RADIO CHANNELS MODELING IN MATLAB
for i=1:length(r) r = sqrt(0.5*(x.^2 + y.^2));
step = 0.1; range = 0:step:3;rt(ki:i*Mi) = r(i); ki = ki+Mi;
end h = hist(r, range);
fr_approx = h/(step*sum(h));r = rt;
fr = (range/0.5).*exp(-range.^2);
With this MATLAB code one can obtain both the “symbol-
level” and “block-level” Rician fading channels for a pro-
per chosen interpolation factor Mi. Also, Rayleigh fading
samples can be obtained for Kdb = -inf. A typical Rician
fading envelope is shown in Fig.1, where the fading ampli-
tudes are plotted in decibels (about the root-mean-squared
(RMS) value).
plot(range, fr_approx,'ko', range, fr,'k');
grid;
0 0.5 1 1.5 2 2.5 3
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
rf(r)
approximated PDF
analytical PDF
Now, we will consider a MATLAB based approxima-
tion of the Rician CDF. In the MATLAB code below, the
Rician CDF is approximated from the derived fading samp-
les according to the m-file rice_fading.
Kdb=7; N=100000; Mi=1;
r=rice_fading(Kdb,N,Mi);
RdB = 20*log10(r);
Rt
for m = 1:length(Rt)
= [min(RdB):max(RdB)];
fade = find(RdB < Rt(m));
Nm = length(fade); AF(m) = Nm/N;
end Fig. 3. The approximated and analytical Rayleigh PDF for σ0
2
= 0.5.
semilogy(Rt,AF,'k-o'); grid;
In the above code the approximated Rayleigh PDF (deno-
ted as fr_approx) is derived in MATLAB by means of
the useful function hist (the histogram function). Then, a
two-dimensional plot is used (by means of the MATLAB
function plot) to compare the approximated PDF with the
analytical PDF (denoted as fr) over a range of interest.
In this example the Rician CDF is derived by means of an
iterative construction, where at each iteration the MAT-
LAB functions find and length are used to obtain the num-
ber of fades, which are below the specified threshold value.
The obtained CDF is plotted in Fig. 2.
Finally, we will consider the generation of correlated
Rayleigh-distributed fading samples by using the modified
sum-of-sinusoids method as described in [8]. The quadra-
ture components of Rayleigh fading process are given by
-20 -15 -10 -5 0 5 10
10
-3
10
-2
10
-1
10
0
logCDF
Amplitude/RMS (dB)
∑
=
+=
M
n
nndt
M
tx
1
)coscos(
2
)( φαω , (10)
∑
=
+=
M
n
nndt
M
ty
1
)sincos(
2
)( ϕαω , (11)
with
Mn
M
n n
n ...,,2,1,
4
2
=
+−
=
θππ
α , (12)
where ωd is the maximum angular Doppler frequency, φn,
ϕn and θn are statistically independent and uniformly dis-
tributed on [–π, π) for all n. The following m-file, named
ray_doppler, exploits equations (9)-(12) for correlated
Rayleigh-distributed fading samples generation in MAT-
LAB.
Fig. 2. An approximated Rician CDF for K = 7 dB.
The Rician CDF in Fig.2 is plotted on a logarithmic proba-
bility scale, which allows us to expand the tail of the CDF,
where for example the 10 dB fading margin overload pro-
bability is seen to be approximately 10-2
.
function r = ray_doppler(fm, M, dt, N)The next MATLAB code is an example construction
for comparing an approximated Rayleigh PDF with the cor-
responding analytical PDF given by (4). The obtained re-
sult is shown in Fig. 3.
T = N*dt-dt; t = 0:dt:T;
c = sqrt(2/M); w = 2*pi*fm; x = 0; y = 0;
for n = 1:M
alpha = (2*pi*n-pi+(2*pi*rand-pi))/(4*M);
ph1 = 2*pi*rand - pi;N = 100000;
ph2 = 2*pi*rand - pi;x = randn(1, N); y = randn(1, N);
x = x + c*cos(w*t*cos(alpha) + ph1);
4. RADIOENGINEERING, VOL. 12, NO. 4, DECEMBER 2003 15
y = y + c*cos(w*t*sin(alpha) + ph2);
end
r = sqrt(x.^2 + y.^2)/sqrt(2);
Input arguments of the m-file ray_doppler are the maxi-
mum Doppler frequency (denoted as fm) in Hz, the number
of sinusoids (denoted as M), the time step (denoted as dt)
and the desired fading sequence length (denoted as N). All
values of φn, ϕn and θn are obtained by means of the MAT-
LAB random number generator rand, which produces uni-
formly distributed random numbers. Using proper values
for M (M should be not less than eight [8]), N and dt, one
can obtain the desired Doppler spread. The considered
approach can be extended with minor additions for correla-
ted Rician fading samples generation.
4. Monte Carlo Simulation Example
Let us consider a transmission of digitally modulated
symbols over an uncorrelated flat Rician fading channel.
Then, if si denotes the transmitted symbol at the ith time
instant, the received symbol vi can be expressed as
iiii nsrv +⋅= , (13)
where {ri} denotes a sequence of independent Rician-dis-
tributed random variables and ni’s are samples of a comp-
lex, zero-mean white Gaussian noise process with one-si-
ded power spectral density N0. A MATLAB m-file, named
psk_rice, is given below, wherein the performance of pha-
se shift keying (PSK) signaling over such a fading channel
is simulated. It should be mentioned that the simulation
example requires the Communications Toolbox of MAT-
LAB and the m-file rice_fading in order to run.
function BER = psk_rice(logEbNo,M,Kdb)
k = log2(M); EbNolin = 10.^(logEbNo/10)
Fd = 1; Fs = 1; Nit = 100000; Ns = 1000;
Tstop = 100;
for it_snr = 1:length(EbNolin)
nstd = sqrt(1/(2*k*EbNolin(it_snr)));
bit_err = 0;
for it = 1:Nit
a = randint(Ns,1,M);
s = dmodce(a,Fd,Fs,'psk',M);
r = rice_fading(Kdb,Ns,1); v_r = s.*r';
v = v_r + nstd*(randn(Ns,1) + ...
j*randn(Ns,1));
z = ddemodce(v, Fd, Fs,'psk',M);
errors = biterr(a,z);
bit_err = bit_err + errors;
if bit_err >= Tstop
break
end
end
B
end
ER(it_snr) = bit_err/(it*Ns*k);
semilogy(logEbNo, BER,'k');
xlabel('EbNo(dB)'); ylabel('BER'); grid;
Input arguments of the m-file psk_rice are the vector
logEbNo of energy-per-bit to noise power spectral density
values (in decibels), the PSK constellation size M and the
Rician K-factor Kdb in decibels. The Communications
Toolbox functions used in the simulation example are:
randint (generate matrix of uniformly distributed random
integers), dmodce (baseband digital modulator),
ddemodce (digital baseband demodulator) and biterr
(compute number of bit errors and bit error rate). Notice
how the for-end loops are used in the simulation. The outer
loop is used for signal-to-noise ratio (SNR) points enume-
ration, while (for each SNR point) the inner loop iterates a
finite number of frames of PSK symbols until a threshold
value of bit errors is reached (thanks to the if-break-end
construction) or the total number of frames is executed.
Finally, the estimated bit error rate (BER) is plotted versus
the SNR points by means of the MATLAB function
semilogy. It should be mentioned that the simulation accu-
racy is determined by the number of errors observed. A
rule of thumb is that after 100 errors the estimated BER is
within a factor 1.3 of the true BER (with approximately 99
percent confidence). So, a threshold value of 100 bit errors
is used in the simulation for early stopping the inner loop
iterations. One can also apply a set of SNR-dependent
threshold values to avoid a time-consuming simulation.
The simulation result is shown in Fig.4 for quadrature pha-
se shift keying (QPSK) signaling and two different Rician
K-factors (given in decibels).
0 5 10 15 20 25
10
-4
10
-3
10
-2
10
-1
10
0
Eb/No (dB)
BER
Kdb = -inf
Kdb = 5
Fig. 4. Bit error rate performance of QPSK signaling over an
uncorrelated Rician fading channel.
5. Conclusions
In this paper, an approach to demonstrate mobile
radio channels modeling in MATLAB is presented. The
basic types of small-scale fading channel models are
derived and simulated using MATLAB. The developed
channel models can be extended with minor additions to
model other types of fading channels (for example, a
correlated Rician fading channel). Further, simple and
useful MATLAB constructions for approximation of CDFs
and PDFs are also given. Finally, the presented Monte
Carlo simulation example can be used as a framework for
performance estimation of various digital modulation
schemes in MATLAB.
5. 16 N. KOSTOV, MOBILE RADIO CHANNELS MODELING IN MATLAB
References
[1] SKLAR, B. Rayleigh fading channels in mobile digital communica-
tion systems, Part I: Characterization. IEEE Communications Maga-
zine, 1997, vol. 35, no. 7, p. 90 - 100.
[2] SUZUKI, H. A statistical model for urban radio propagation. IEEE
Transactions on Communications, 1977, vol. COM-25, no. 7, p. 673
to 680.
[3] PROAKIS, J. G. Digital communications. 2nd
ed. New York:
McGraw-Hill, 1989.
[4] CLARKE, R. H. A statistical theory of mobile-radio reception. Bell
Systems Technical Journal, 1968, vol. 47, no. 6, p. 957 - 1000.
[5] JAKES, W. C. Microwave mobile communications. New York:
Wiley, 1974.
[6] PATZOLD, M., KILLAT, U., LAUE, F., LI, Y. On the statistical
properties of deterministic simulation models for mobile fading
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[7] HOEHER, P. A statistical discrete-time model for the WSSUS multi-
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About Author
Nikolay KOSTOV was born in Varna, Bulgaria, on Au-
gust 7, 1969. He received Dipl. Eng. and Dr. Eng. degrees
from the National Military University of Veliko Turnovo,
Bulgaria, in 1993 and 1999, respectively. He joined the
Radio Engineering Department at Technical University of
Varna, Bulgaria, in March 2001, where he is currently ser-
ving as an Assistant Professor. His research interests inclu-
de source/channel coding, modulation techniques, and
communications over fading channels.
Book Review:
Multimedia Communications. Multimedia Technology and Watermarking
Dušan Levický, Technical University of Košice
The monograph Multimedia communications written
by Dušan Levický, a professor of Electrical Engineering at
the Technical University of Košice tries to cover a full
spectrum of multimedia systems, methods and standards.
Many conferences and journals have been devoted to
the multimedia in several last years. Numerous standards,
coding methods and other techniques have been developed.
It is not easy to get desired detailed information from this
area or to obtain a general overview on multimedia. We
suppose, this could be the main reason for writing the mo-
nograph.
The first three chapters are devoted to the multimedia
systems, multimedia services and to the classification of
multimedia signals.
Chapter 4 presents basics of compression methods for
multimedia. The short but important last section of the
Chapter 4 contains evaluation methods of the decompres-
sed information quality. International digital facsimile co-
ding standards are described in Chapter 5.
Chapters 6, 7 and 8 present coding of pictures and
image sequences.
Existing digital video-coding standards are summari-
zed in Chapter 9.
Chapter 10 gives an introduction to speech-coding
standards, including standards for mobile communications.
Audio-coding standards are given in Chapter 11.
Chapter 12 is devoted to watermarking digital image
and video data.
The book contains list of references, list of standards
and a useful index.
It seems, the reviewed book successfully fills the gap
in the Slovak and Czech literature. Reviewers can recom-
mend Multimedia communications to any engineer, techni-
cian, student and researcher interested in this subject.
LEVICKÝ, D. Multimedia Communications. Multimedia
technology and Watermarking. Košice: Elfa s.r.o., 2003.
Address of the bookseller: Elfa, s.r.o. , Letná 9,
04200 Košice, Slovakia, knihy@elfa.sk
Price: 149 SK
Reviewers: Vladimír Šebesta and Stanislav Hanus