This paper addresses the bit-rate reduction of MPEG-2 compressed video and presents a method to reduce requantization errors in transcoding. The proposed method assumes Laplacian distributions for the original AC coef...
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ISBN:
(纸本)0780362977
This paper addresses the bit-rate reduction of MPEG-2 compressed video and presents a method to reduce requantization errors in transcoding. The proposed method assumes Laplacian distributions for the original AC coefficients of the DCT. A Laplacian parameter for each coefficient is estimated at the transcoder from the quantized input DCT coefficients. These parameters are then used in requantization to improve the quality of the transcoded video. The algorithm provided in this paper to estimate the Laplacian parameters of the original DCT coefficients is simple to implement and may be adapted to other DCT-based coding schemes.
An analytical approach is developed for evaluating the expected range increase and variations in coverage range, while using an M-element adaptive antenna array at the base station (BS). The analysis is based on the m...
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An analytical approach is developed for evaluating the expected range increase and variations in coverage range, while using an M-element adaptive antenna array at the base station (BS). The analysis is based on the match filter bound an the bit error rate probability for a frequency non-selective Rayleigh fading channel. Results for a ten element uniform linear array (ULA) indicate the expected range increase over a BS with only a single antenna can be nearly doubled. A 1.6 to 1.7 increase is also likely with a five-element array.
Cellular systems using adaptive antennas for spatial processing have been shown to provide an increase in capacity. When employing adaptive antennas, the standard approach to achieve capacity gain has been to maximize...
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Cellular systems using adaptive antennas for spatial processing have been shown to provide an increase in capacity. When employing adaptive antennas, the standard approach to achieve capacity gain has been to maximize the link quality between the mobile and base station via optimum combining. This paper presents an alternative optimization approach based on optimizing the adaptive antenna array to maximize the trunking efficiency, of which the effect was subsequently an outstanding issue. Monte Carlo simulations, substantiated with theoretical analysis, were used to evaluate this issue. Based on the analysis, the proposed approach could increase the capacity by 2 to 4 times.
A multifilter is a filter with matrix-valued coefficients, and is used in the processing of vector-valued signals, e.g. color images. Convolution becomes a vector sum of matrix-vector multiplication. In this paper, we...
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A multifilter is a filter with matrix-valued coefficients, and is used in the processing of vector-valued signals, e.g. color images. Convolution becomes a vector sum of matrix-vector multiplication. In this paper, we efficiently implement a multifilter as a parallel combination of scalar filters. Each scalar filter works on one component of the input vector signal, which increases processing speed by the dimension of the vector-valued signal. This means that by using N processors, the throughput is increased by a factor of N while the total memory usage remains unchanged. We also present a frequency-domain analysis of the filtering.
A transmission channel used in application such as telecommunications can be modeled as a bandpass filter. Measurement of the frequency selectivity of the channel is important to ensure that the information-bearing si...
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A transmission channel used in application such as telecommunications can be modeled as a bandpass filter. Measurement of the frequency selectivity of the channel is important to ensure that the information-bearing signal has minimal distortion and loss of information. A comparison is made for several methods used for estimating the frequency selectivity of the transmission. The methods presented are the correlation method, instantaneous energy and frequency estimation and the cross Wigner-Ville distribution. The theoretical foundations and assumptions are described for each method. In general, all the methods gave similar performance in terms of the frequency selectivity. Due to the shorter analysis duration, both the instantaneous energy and frequency estimation and cross Wigner-Ville distribution is ideal for estimating the frequency selectivity of time-varying channels.
In this paper, a new blind adaptive multiuser detector, which is termed the prediction least mean kurtosis (PLMK) algorithm, is proposed for joint MAI and narrowband interference (NBI) suppression in asynchronous CDMA...
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ISBN:
(纸本)0780359887
In this paper, a new blind adaptive multiuser detector, which is termed the prediction least mean kurtosis (PLMK) algorithm, is proposed for joint MAI and narrowband interference (NBI) suppression in asynchronous CDMA systems. This algorithm is based on higher-order statistics rather than the second-order statistics used in the LMS algorithm. Unlike the regular least mean kurtosis (LMK), it takes into consideration samples earlier than those corresponding to the current bit. For comparison purposes, we also apply the regular LMK algorithm to the case of asynchronous CDMA systems. Simulation results show that the blind adaptive multiuser detector with PLMK algorithm provides significantly better performance than the one with regular LMK algorithm.
作者:
R. BaghaieSignal Processing Laboratory
Department of Electrical and Communications Engineering Helsinki University of Technology P.O. BOX 3000 02015 HUT Finland
In code division multiple access receivers, in order to suppress the multiple access interference, different multiuser detectors such as the decorrelating and the linear minimum mean square error detectors can be util...
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In code division multiple access receivers, in order to suppress the multiple access interference, different multiuser detectors such as the decorrelating and the linear minimum mean square error detectors can be utilized. In order to alleviate the implementation complexity, iterative implementation of such detectors have been reported. Two most popular iterative algorithms used in such detectors are the Steepest Descent (SD) and the Conjugate Gradient (CG) algorithms. In this paper, we first compare fixed-point and floating-point performances of these algorithms. Furthermore, hardware implementations of the algorithms are compared. Based on these comparisons, for the implementation of the SD algorithm a systolic architecture is proposed.
In this paper, we propose a novel approach for computing real-valued discrete transforms such as the discrete cosine transform and the discrete Hartley transform. The approach is based on the algebraic integer encodin...
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In this paper, we propose a novel approach for computing real-valued discrete transforms such as the discrete cosine transform and the discrete Hartley transform. The approach is based on the algebraic integer encoding scheme. With the aid of this scheme, an error-free representation of the cos, sin and cas functions becomes possible. Furthermore, for the implementation of these algorithms a fully pipelined systolic architecture with O(N) throughput is proposed.
The edge and motion are the main features that human visual system (HVS) perceives intensively. This paper proposes an algorithm for the segmentation of the moving object with accurate boundary using color and motion ...
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Stereophonic sound becomes more important in a growing number of hands-free applications where spatial realism is demanded. Such hands-free systems need stereophonic acoustic echo cancellers to reduce echoes that resu...
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Stereophonic sound becomes more important in a growing number of hands-free applications where spatial realism is demanded. Such hands-free systems need stereophonic acoustic echo cancellers to reduce echoes that result from coupling between loudspeakers and microphones. In this paper, we propose a new adaptive algorithm for an stereophonic acoustic echo canceller based on human auditory properties and affine projection (AP) algorithm. The proposed algorithm employs a pre-processor generating speech-like noise to decorrelate the input signals without degrading perceptual speech quality. The decorrelation is based on the masking patterns of the human auditory system. By showing that the AP algorithm can be represented by a vector update as a combination of the Gram-Schmidt (GS) orthogonalization followed by the normalized LMS (NLMS) algorithm, the proposed adaptive algorithm integrates the pre-processor into the adaptive algorithm. Subjective listening test and computer simulation show the effectiveness of the proposed algorithm.
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