nils-herrmann/clean_scirepeval huggingface dataset:
A MIMO SFBC OFDM scheme for transmission of watermarked medical images over frequency-selective fading channels

Digital watermarking is a technique adapted to embed patient information as watermark with medical images to reduce storage and transmission overheads. A multiple-input multiple-output (MIMO) transmission scheme in which multiple antennas are used in both transmitter and receiver has emerged as one of the most significant technical breakthroughs in modern wireless communications. This paper presents a MIMO SFBC OFDM scheme for transmission of watermarked medical images over frequency-selective fading channels and its performance is analyzed in comparison with SISO-OFDM using MMSE V-BLAST based detection at the receiver. The efficacy of the proposed scheme is illustrated with implementation results on two watermarked medical images.
Adaptive filtering approaches for colour image and video restoration

An adaptive simplified model Kalman filter (ASMKF) is developed for image and video impulsive noise suppression. The ASMKF is more effective than the median filter (MF) and the robust reduced update Kalman filter (RRUKF) in suppressing the impulsive noise, especially when the signal-to-noise ratio is low. Further, a hybrid filter is presented for colour image and video restoration in a mixed noise environment, where both the impulsive and correlated noise may be present. The proposed hybrid filter is composed of two stages, where the first stage removes the impulsive noise while the second removes the correlated noise. The ASMKF is suggested for the first stage of the hybrid filter. In the second stage of the proposed hybrid filter, a discrete wavelet transform (DWT) filter formulated using a biorthogonal wavelet with adaptive shrinkage is applied on the impulsive-noise-free image obtained from the first stage. The efficacy of the developed ASMKF and the proposed hybrid filter are illustrated through implementation results on colour image and video restoration.
A relationship between the structures of the radix-2 DIT FHT and complex-valued FFT algorithms

By reformulating the existing radix-2 decimation-in-time (DIT) FHT and complex-valued FFT algorithms using an efficient index mapping, a close relationship between the two algorithms is established. A detailed comparison between the two algorithms is carried out. It is shown that these algorithms have similar structures and can be implemented using the same butterfly. In view of this relationship and the fact that the DHT is an efficient alternative to the DFT for real data, it should be possible to use a single software or hardware module to compute the DHT as well as the forward and inverse complex-valued DFTs.
An Adaptive Space-Time Multiuser Detection Algorithm for CDMA Systems

Based on the minimum mean squared error (MMSE) between the data stream and the linear combiner output, a new multiuser detection (MUD) algorithm that combines space-time (ST) processing and antenna diversity on direct-sequence CDMA signals is proposed. The new ST-MUD algorithm does not require explicit estimation of channel and signaling information, as such it avoids any channel estimation error and provides robust and accurate results. An adaptive implementation of the new ST-MUD algorithm using training sequences is given and simulated. The new ST-MUD algorithm provides a performance better than that of existing algorithms and is especially suitable for CDMA systems
Computer-aided analysis of wave digital filters

An original computer-aided analysis package of the Swamy-Thyagarajan wave digital filter structures has been developed, by the authors, on the minicomputer PDP 11/45 GT-44 Graphics System. The package utilizes the chain matrices of the digital two-ports of the Swamy-Thyagarajan wave digital filter structures which are expressed in terms of the coefficient multipliers of the digital two-ports and the Z variable. The elements and values of a doubly terminated LC ladder can be entered on a cathode ray tube display by utilizing the interactive graphics capability of a light pen. The ladder is then transformed into the Swamy-Thyagarajan wave digital filter structures. Port resistances, coefficient multipliers, chain matrices, the coefficients of the digital filter transfer function, transformed lowpass, highpass, bandstop and bandpass filters can be obtained. The package provides numerical values of the amplitude and phase responses, and plots the responses on the cathode ray tube display.
Class of nonuniform multilayer RC distributed networks

A simple alternative solution is given to the problem of obtaining the network parameters of a class of multilayer RC lines considered recently by Singhal and Wing. It is further shown that, as in the single-layer lines, the transmission parameters are interrelated, and the transposes of these parameters satisfy either the current or the voltage differential equation of the multilayer lines. An exact equivalent circuit, using ideal transformers, is given for this class of multilayer lines in terms of single-layer lines.
Multidimensional vector radix FHT algorithms

In this paper, efficient multidimensional (M-D) vector radix (VR) decimation-in-frequency and decimation-in-time fast Hartley transform (FHT) algorithms are derived for computing the discrete Hartley transform (DHT) of any dimension using an appropriate index mapping and the Kronecker product. The proposed algorithms are more effective and highly suitable for hardware and software implementations compared to all existing M-D FHT algorithms that are derived for the computation of the DHT of any dimension. The butterflies of the proposed algorithms are based on simple closed-form expressions that allow easy implementations of these algorithms for any dimension. In addition, the proposed algorithms possess properties such as high regularity, simplicity and in-place computation that are highly desirable for software and hardware implementations, especially for the M-D applications. A close relationship between the M-D VR complex-valued fast Fourier transform algorithms and the proposed M-D VR FHT algorithms is established. This type of relationship is of great significance for software and hardware implementations of the algorithms, since it is shown that because of this relationship and the fact that the DHT is an alternative to the discrete Fourier transform (DFT) for real data, a single module with a little or no modification can be used to carry out the forward and inverse M-D DFTs for real- or complex-valued data and M-D DHTs. Thus, the same module (with a little or no modification) can be used to cover all domains of applications that involve the DFTs or DHTs.
Automatic modulation type recognition

Identification of the modulation type of a received signal is a problem encountered in radio spectrum surveillance and control. It is attractive to design methods that use only one or two time-domain classification parameters, in order to minimize the computational complexity. A number of new classification parameters are proposed and studied in this paper. They are compared to an existing one-parameter method. Also, a new method of envelope extraction, which does not require Hilbert transform computation, is proposed. The proposed methods achieve better recognition rates at short data records, e.g. 89% vs. 82% at 10 dB, 1024 samples, and 95% for a combination of two parameters.
Design of active distributed RC-filters using exponential lines

New active distributed RC-structures utilizing exponential RC-lines and operational amplifiers are proposed for realizing band-pass transfer functions and transfer functions having both a pair of complex poles and a pair of complex zeros. It is shown that the magnitude of the amplifier gain for a given pole Q decreases with increasing taper. In the case of the structures realizing both complex poles and zeros, it is shown that the sensitivity with respect to the gain of the pole determining amplifier is considerably lower than that of the structure previously proposed by Ghausi and Bello.
On the VLSI implementation of real-time order statistic filters

Real-time implementation of an order-statistic filter (OSF) or ranked order filter requires the computation of the order statistic (ranked order) of the samples in a window which gets periodically updated with the arrival of a new sample(s). The authors give an algorithm for the computation of the running order statistic. A highly parallel architecture suitable for VLSI implementation is presented. The architecture is very versatile, with programmable window size and rank order. An expansion algorithm and its VLSI architecture, which permit the usage of two r-bit OSFs to implement an (r+1)-bit OSF, where r is the resolution of the input signal samples, are given. In a special case where one is satisfied with at most one LSB error, the hardware complexity of the proposed architecture can be reduced by almost one half. It is further shown how a VLSI chip incorporating the proposed architecture can be used as the basic building block in the real-time implementation of other forms of nonlinear filters.
A novel morphology-based classifier for automatic detection of epileptic seizures

Most of the automatic seizure detection schemes reported in the literature are complex for detecting seizures that are of (a) short duration, (b) minimal amplitude evolution, or (c) non-rhythmic mixed frequency epileptic activity. We present a novel morphology-based classifier to detect epileptic seizures for intracranial EEG recording. The method characterizes epileptic seizure by detecting continual presence of sharp half-waves in the EEG. Performance is evaluated on single channel intracranial EEG of seven patients, and compared to two previously developed methods for intracranial EEG recordings by our research group. The method detects seizure of varying types (rhythmic, non-rhythmic, short- and long- seizures) with a sensitivity of 100%, a false detection rate of 0.1/h and an average onset delay of 9.1 s. The method outperforms the two previously developed methods and is computationally simple for real-time application. Preliminary results on seven patients data are very promising.
A two-mode interpolation error concealment MCI scheme

In this paper, we propose a scheme intended for low bit-rate motion-compensated interpolation to improve the quality of low bit-rate video encoded in conjunction with the frame dropping technique. We develop a two-mode interpolation errors concealment (TMIEC) MCI scheme, which exploits the block-based motion vector field available to the decoder and which can work well in both smooth regions and edge regions. Simulation results demonstrate that, with the help of a gradient estimator, TMIEC results in a better subjective quality and objective quality compared to previously proposed schemes.
High-Throughput Memory-Based Architecture for DHT Using a New Convolutional Formulation

A new formulation is presented for the computation of an -point discrete Hartley transform (DHT) from two pairs of [(N/2-1)/2]-point cyclic convolutions, and further used to obtain modular structures consisting of simple and regular memory-based systolic arrays for concurrent pipelined realization of the DHT. The proposed structures for direct-memory-based implementation is found to involve nearly the same hardware complexity as those of the existing structures, but offers two to four times more throughput and two to four times less latency compared with others. The distributed-arithmetic (DA)-based implementation is also found to offer very less memory-complexity and considerably low area-delay complexity compared with the existing DA-based structures.
New Spatially Adaptive Wavelet-based Method for the Despeckling of Medical Ultrasound Images

Medical ultrasound images are widely used for diagnostic purposes. A major problem regarding these images is in their inherent corruption by speckle noise in a multiplicative fashion. The presence of speckle noise severely hampers the interpretation and analysis of medical ultrasound images. This paper presents a fast and reliable wavelet-based method for reducing the speckle in medical ultrasound images. A wavelet-based Bayesian maximum a posteriori denoiser is developed in a homomorphic framework. The wavelet coefficients of the log-transformed signal are modelled by a conditional Gaussian distribution, whereas those of the log-transformed speckle with a Maxwell distribution. The signal variances are obtained by using the local neighbors thus, making the method spatially adaptive. Simulations are performed using synthetically speckled and real ultrasound images. The results show that the proposed method can perform better than some of the existing methods in terms of the signal-to-noise ratio. Furthermore, the proposed method is fast, and preserves diagnostically important details.
Fine granularity spatially adaptive regularization for TVL1 based image deblurring

A total variation weighted l1 (TVWL1) norm based image dublurring algorithm is proposed. The proposed algorithm uses a series of data matrix to weight the error signal and then the l1 norms of the resultant series of error signals are used to produce the fidelity term while the regularization term remains the conventional total variation regularization. An alternate minimization approach is used to solve the minimization problem that comprises the fidelity and the regularization terms. It is shown through simulation results that the proposed TVWL1 algorithm offers the same robustness with respect to impulsive noise as that achieved by using the recently proposed total variation l1 (TVL1) algorithm, while yielding an improved signal-to-noise ratio (SNR), and hence, improved restoration in image deblurring.
Efficient Application of MUSIC Algorithm Under the Coexistence of Far-Field and Near-Field Sources

This correspondence is concerned with source localization and classification for scenarios where both the far-field and near-field narrowband sources may coexist. We propose an efficient MUSIC-based solution that requires neither a multidimensional search nor high-order statistics (HOS). We also derive the stochastic Cramér-Rao bound (CRB) for the problem under consideration. The performance of the proposed method is compared with an existing method and with the CRB.
Separation of close sinusoids by cross-coupled phase locked loop

A study is made of a cross-coupled phase-locked loop (CCPLL) used for separation of close sinusoids with slowly varying frequencies. It is assumed that the sinusoids have equal amplitudes, and it is shown that the CCPLL system can effectively separate two sine signals with an observation interval T<1/ Delta f. An analysis in the presence of noise is also given. It is shown that a satisfactory phase estimation can be achieved for SNR >or=15 dB. The result has application in fields such as ranging, symbol synchronization, and carrier recovery for coherent demodulation.<<ETX>>
A closed-form solution for the design of complex FIR filters and its application to filter banks

In this paper, the least-square design problem of complex FIR filters with arbitrary frequency response characteristics is investigated. A closed-form solution is obtained by solving the approximation problem analytically, enabling a very fast calculation of the impulse response of the filter to be designed. An application of the derived solution to QMF bank design is explored. By using the Butterworth approximation to obtain an IIR filter for the analysis part and by employing the closed-form solution to approximate a nonlinear-phase FIR filter for the synthesis part, a class of nearly perfect-reconstruction QMF bank is developed. It is shown that the mixed IIR/FIR filter bank not only has a very good reconstruction performance but also enjoys an extremely low design complexity.
New techniques for multi-resolution motion estimation

We investigate three new methods to predict motion vectors (MVs) across subbands for multi-resolution motion estimation (MRME): linear prediction, median filtering (MF), and multi-candidate techniques. Compared to the conventional MRME techniques, the proposed linear-prediction-based and the MF-based techniques effectively overcome the problem of propagation of false MVs. A significant feature of these two techniques is that they impose no demand for additional bandwidth, and simulation studies show that they not only improve prediction performance, but also reduce the number of bits needed to encode the motion information. It is further shown that the improvement in the performance thus achieved involves little increase in computational complexity.
An efficient three-dimensional decimation-in-time FHT algorithm based on the radix-2/4 approach

In this paper, a decimation-in-time (DIT) fast Hartley transform (FHT) algorithm is proposed for efficient computation of the three-dimensional (3-D) discrete Hartley transform (DHT). It is based on a mixture of radix-(2/spl times/2/spl times/2) and radix-(4/spl times/4/spl times/4) index maps. The proposed algorithm substantially reduces the number of arithmetic operations compared to the existing 3-D radix-(2/spl times/2/spl times/2) FHT algorithms.
Characterization of nonuniform perfect-reconstruction filterbanks using unit-step signal

An algebraic characterization of nonuniform perfect reconstruction (PR) filterbanks with integer decimation factors is presented. The PR property is formulated in the z domain based on the response of the linear multirate systems to the delayed unit-step signals. This leads to a unique class of characterizing formulas that are necessary and sufficient conditions for the PR property and free from the complex roots of unity. Two related characterizations of nonuniform PR systems, in the form of necessary conditions, are also developed based on these formulas. As a concrete example, the results are then used to derive necessary and sufficient conditions for PR nonuniform delay chain filterbanks. The conditions show that nonuniform delay chain filterbanks are the signal processing realizations of the mathematical notion of the exact covering systems of congruence relations. Important results from the mathematics literature on the exact covering systems are introduced. The results elucidate the admissible factors of decimation for the nonuniform PR delay chain systems in settings with maximally distinct decimation factors. A simple test of the PR property for delay chain systems is also presented. The test is based on the divisibility of certain polynomials by the cyclotomic polynomials. Finally, multirate systems based on the Beatty sequences, which are the irrational generalization of the exact covering systems, are briefly discussed.
Joint Optimal Multipath Routing and Rate Control for Multidescription Coded Video Streaming in Ad Hoc Networks

This paper studies an important problem, namely, the joint multipath routing and rate control for multidescription coded (MD-coded) video streaming in wireless ad hoc networks. In addition to selecting a pair of paths to optimize the expected end-to-end video quality, we also explore an optimal packet skipping strategy for the rate control in order to minimize the impact of the skipped packets on the quality of the video. The R-D hint information, consisting of the size of the packets in bits and the importance of the packets for reconstructing the video, is used to characterize the packets in an R-D sense. Since searching for paths to minimize the expected end-to-end video distortion by simultaneously considering the skipped packets prior to the transmission and those dropped/delayed during the transmission is a highly complex problem and is expected to be NP-hard, we develop a heuristic greedy-relaxation-based routing solution that enables the system to efficiently select near-optimal paths. Extensive simulation studies have been conducted to compare the performance of the proposed algorithm with that of several existing algorithms, showing the superior performance of the proposed one. Such a joint rate control and multipath routing approach provides an important methodology for high-quality real-time video streaming applications over ad hoc wireless networks.
On the computation of running discrete cosine and sine transform

Two algorithms are given for the computation of the updated discrete cosine transform-II (DCT-II), discrete sine transform-II (DST-II), discrete cosine transform-IV (DCT-IV), and discrete sine transform-IV (DST-IV). It is pointed out that the algorithm used for running DCT-IV can also be used for computation for running DST-IV without additional computational overhead. An architecture which is common and suitable for VLSI implementation of the derived algorithms is also presented. Preliminary studies have shown that the architecture can easily be implemented in VLSI form, and, in conjunction with a high-speed digital signal processor (for example ADSP 2100A), it can be used for real-time transform domain LMS adaptive filtering (128 taps) of 8 kHz sample rate speech signals.
Partial-Update ${L}_{\infty}$ -Norm Based Algorithms

The computational complexity of an adaptive filtering algorithm increases with increasing the filter tap length and therefore, the use of such a filter can become prohibitive for certain applications, especially for real-time implementation. In this paper, we develop low-complexity adaptive filtering algorithms by incorporating the concept of partial updating of the filter coefficients into the technique of finding the gradient vector in the hyperplane based on the Linfin-norm criterion. Two specific partial update algorithms based on the sequential and M-Max coefficient updating are proposed. The statistical analyses of the two algorithms are carried out, and evolution equations for the mean and mean-square of the filter coefficient misalignment as well as the stability bounds on the step size are obtained. It is shown that the proposed partial update algorithm employing the M-Max coefficient updating can achieve a convergence rate that is closest to that of the full update algorithm. Finally, simulations are carried out to validate the theoretical results and study the convergence rate of the proposed algorithms
An efficient split-radix FFT algorithm

In this paper, an efficient split-radix FFT algorithm is proposed for computing the length-2/sup r/ DFT that reduces significantly the number of data transfers, index generations, and twiddle factor evaluations or accesses to the lookup table. It is shown that the arithmetic complexity of the proposed algorithm is no more than that of the existing split-radix algorithm. The basic idea behind the proposed algorithm is that a radix-2 and a radix-8 index maps are used instead of a radix-2 and a radix-4 index maps as in the classical split-radix FFT. In addition, since the algorithm is expressed in a simple matrix form using the Kronecker product, it facilitates an easy implementation of the algorithm, and allows for an extension to the multidimensional case.
Integer frequency offset detection with reduced complexity in OFDM systems

In this paper, a novel pilot-aided algorithm is proposed for the detection of integer frequency offset (IFO) in orthogonal frequency division multiplexing (OFDM) systems. By transforming the IFO into two new integer parameters, the proposed method can largely reduce the number of trial values for the true IFO. The two new integer parameters are detected using two different pilot sequences, a periodic pilot sequence and an aperiodic pilot sequence. It is shown that the new scheme can significantly reduce the computational complexity while achieving almost the same performance as compared to previous methods.