Power allocation scheme for multicell interference coordination in OFDMA systems

To coordinate inter-cell interference, a multicell adaptive power allocation scheme is proposed for downlink orthogonal frequency division multiple access (OFDMA) cellular systems. This scheme uses the difference of the signal to interference plus noise ratio (SINR) between the co-subchannels of adjacent cells to balance SINR for coordinating the transmit power in the co-subchannels. The scheme can improve edge user performance, reduce interference between the co-subchannels of adjacent cells and improve radio resource utility. Simulation results show that the scheme can balance system performance and ensure system throughput. __________ Translated from Journal of Beijing University of Posts and Telecommunications, 2008, 31(1): 71–74 [译自: 北京邮电大学学报]     

Design and implement of the signal generator in the magnetic focused conductivity tomography system

To improve stability and performance of the signal source and sweeping detection, as well as to extract abundant and reliable signal, the direct digital synthesis technology was employed to design the generator of the source which formed sweeping frequencies of sine wave output from 1 to 20 MHz. The planar spiral coil was connected as an amplitude modulation circuit. The same coil adopted differential architecture for signal detection and extraction. The MC1595 was utilized to compose a phase detector in which difference of phases varies with the change of frequencies. A low pass filter was designed to filter the carry waves of the sweeping source. Thereby the system gained abundant data and its stability was improved. Further, the spatial resolution of the system was enhanced. All of the above favors the use of software in the magnetic focused conductivity tomography system (MFCT) to reconstruct the image of conductivity within the human body. Translated from Journal of Sichuan University (Engineering Science Edition), 2006, 3(2): 155–158 [译自: 四川大学学报 (工程科学版)]     

Parameter estimation for MIMO system based on MUSIC and ML methods

The frequency offset and channel gain estimation problem for multiple-input multiple-output (MIMO) systems in the case of flat-fading channels is addressed. Based on the multiple signal classification (MUSIC) and the maximum likelihood (ML) methods, a new joint estimation algorithm of frequency offsets and channel gains is proposed. The new algorithm has three steps. A subset of frequency offsets is first estimated with the MUSIC algorithm. All frequency offsets in the subset are then identified with the ML method. Finally, channel gains are calculated with the ML estimator. The algorithm is a one-dimensional search scheme and therefore greatly decreases the complexity of joint ML estimation, which is essentially a multi-dimensional search scheme. __________ Translated from Journal of Electronics and Information Technology, 2008, 30(7): 1552–1556 [译自: 电子与信息学报]     

Indoor and outdoor people detection and shadow suppression by exploiting HSV color information

An adaptive background model based on maximum statistical probability and a shadow suppression scheme for indoor and outdoor people detection by exploiting hue saturation value (HSV) color information is proposed. To obtain the initial background scene, the frequency of R, G, and B component values for each pixel at the same position in the learning sequence are respectively calculated; the R, G, and B component values with the biggest ratios are incorporated to model the initial background. The background maintenance, or the socalled background re-initiation, is also proposed to adapt to scene changes such as illumination changes and scene geometry changes. Moving cast shadows generally exhibit a challenge for accurate moving target detection. Based on the observation that a shadow cast on a background region lowers its brightness but does not change its chromaticity significantly, we address this problem in the article by exploiting HSV color information. In addition, quantitative metrics is introduced to evaluate the algorithm on a benchmark suite of indoor and outdoor video sequences. The experimental results are given to show the performance of the algorithm. __________ Translated from Journal of Huaqiao University (Natural Science), 2007, 28(1): 30–33 [译自: 华侨大学学报 (自然科学版)]     

Image adaptive RST invariant watermark using pseudo-Zernike moments

Rotation, scaling and translation (RST) attacks can desynchronize watermark detection, which causes failure in many watermarking systems. In this paper, an image adaptive RST invariant watermark (AWPZM) is proposed by using the rotation invariant property of pseudo-Zernike moments (PZM) and oddeven quantization. PZM of the original image is computed first, and then those suitable for watermark generation are selected. Then, magnitudes of them are odd-even quantized to generate the watermark. In detection, a normalized hamming function is employed to determine the similarity of the watermark. Experimental results show its robustness to rotation and scaling. For traditional attacks, such as JPEG compression, added noise and filtering, the similarities are all above 0.95. __________ Translated from Journal of Xidian University, 2007, 34(1): 38–42 [译自: 西安电子科技大学学报]     

Routing and wavelength assignment in hierarchical WDM networks

A new routing and wavelength assignment method applied in hierarchical wavelength division multiplexing (WDM) networks is proposed. The algorithm is called offline band priority algorithm (offline BPA). The offline BPA targets to maximize the number of waveband paths under the condition of minimum number of wavelengths, and solve the routing and wavelength assignment (RWA) problem with waveband grooming to reduce cost. Based on the circle construction algorithm, waveband priority function is introduced to calculate the RWA problem. Simulation results demonstrate that the proposed algorithm achieves significant cost reduction in WDM network construction. __________ Translated from Journal of Shanghai Jiaotong University, 2007, 41 (5): 747–750 [译自: 上海交通大学学报]     

Robust adaptive beamforming algorithm based on Bayesian approach

The performance of adaptive array beamforming algorithms substantially degrades in practice because of a slight mismatch between actual and presumed array responses to the desired signal. A novel robust adaptive beamforming algorithm based on Bayesian approach is therefore proposed. The algorithm responds to the current environment by estimating the direction of arrival (DOA) of the actual signal from observations. Computational complexity of the proposed algorithm can thus be reduced compared with other algorithms since the recursive method is used to obtain inverse matrix. In addition, it has strong robustness to the uncertainty of actual signal DOA and makes the mean output array signal-to-interference-plus-noise ratio (SINR) consistently approach the optimum. Simulation results show that the proposed algorithm is better in performance than conventional adaptive beamforming algorithms. __________ Translated from Journal of Northeastern University (Natural Science), 2007, 28(6): 793–796 [译自: 东北大学学报 (自然科学版)]     

FDTD analysis of ground-penetrating radar antennas with shields and absorbers

One of the most critical hardware components of a ground-penetrating radar (GPR) is the antenna system. Important parameters of antennas, such as antenna bandwidth, radiation waveform and cross coupling determine the GPR system performance. The modified TEM horn antenna with distributed resistor load is presented in this paper, and the radiation properties of the antenna with the shields and absorbers are studied through the three-dimensional finite-difference time-domain (FDTD) scheme. Simulations show that the direct signal coupled from the transmitter is decreased by means of the shields and absorbers. Therefore, using the antenna in the GPR system can improve the signal-to-clutter ratio and the dynamic range of the system. __________ Translated from Chinese Journal of Radio Science, 2006, 21(3): 422–427 [译自: 电波科学学报]     

Fixed-point blind source separation algorithm based on ICA

This paper introduces the fixed-point learning algorithm based on independent component analysis (ICA); the model and process of this algorithm and simulation results are presented. Kurtosis was adopted as the estimation rule of independence. The results of the experiment show that compared with the traditional ICA algorithm based on random grads, this algorithm has advantages such as fast convergence and no necessity for any dynamic parameter, etc. The algorithm is a highly efficient and reliable method in blind signal separation. __________ Translated from Journal of Taiyuan University of Technology, 2007, 38(1): 35–37 [译自: 太原理工大学学报]     

Embedded coding of medical images with regions of interest based on 3-D zerotree

In order to satisfy the need of diagnoses, based on the characteristic of medical images that a sequence of frames are formed in one body inspection, a new strategy for medical images compression is proposed. The 3-D wavelet is adopted and the planar zerotree is extended to the 3-D zerotree. By making use of the 3-D zerotree structure, a simple method for region of interest (ROI) mask generation is put forward. Medical images are compressed by three-dimensional embedded coding with the compression of regions of interest. Simulation results have shown that it can efficiently improve the compression ratio without affecting the diagnoses. Translated from Journal of Xidian University, 2006, 33(2): 182–185 [译自: 西安电子科技大学学报]     

Compression algorithm for electrocardiograms based on sparse decomposition

Sparse decomposition is a new theory in signal processing, with the advantage in that the base (dictionary) used in this theory is over-complete, and can reflect the nature of a signal. Thus, the sparse decomposition of signal can obtain sparse representation, which is very important in data compression. The algorithm of compression based on sparse decomposition is investigated. By training on and learning electrocardiogram (ECG) data in the MITBIH Arrhythmia Database, we constructed an overcomplete dictionary of ECGs. Since the atoms in this dictionary are in accord with the character of ECGs, it is possible that an extensive ECG datum is reconstructed by a few nonzero coefficients and atoms. The proposed compression algorithm can adjust compression ratio according to practical request, and the distortion is low (when the compression ratio is 20:1, the standard error is 5.11%). The experiments prove the feasibility of the proposed compression algorithm. __________ Translated from Chinese Journal of Biomedical Engineering, 2008, 27 (1): 13–17 [译自: 中国生物医学工程学报]     

A cross-layer adaptive transmission scheme over correlated fading channels

Conventional adaptive transmission schemes perform poorly in wireless correlated slow-fading channels. A cross-layer adaptive transmission scheme combined with selective repeat automatic repeat request (SR-ARQ) is proposed. We apply a multi-state Markov system model for analyzing the performance of systems and optimizing the selection of modulation levels and packet sizes in correlated fading channels, which is also described by a finite-state Markov chain. A general closed-form expression of the average throughput for our suggested scheme is presented. Numerical results show that our adaptive scheme combined with SR-ARQ can obtain good performance in correlated fading channels. Translated from Journal on Communications, 2006, 45(1): 35–41 [译自: 通信学报]     

Positioning models and systems based on digital television broadcasting signals

The requirement and feasibility of the positioning system using digital television (DTV) broadcasting signals are analyzed. The principle of DTV positioning on the basis of frame synchronization is brought forward and the ranging characteristic is studied that the observables are asynchronously measured during the same epoch interval. The models of the pseudo-range observation and Doppler carrier phase integral are researched. The system observation and state equations are presented on the basis of the above models. The simulation results showed that DTV positioning technology could remarkably improve the precision of system state estimates using smoothing methods for positioning systems or integrated navigation systems. The DTV positioning that has a sub-meter level ranging error and meter level positioning accuracy can parallel with and even taken as a beneficial substitute for the tradition positioning technology. __________ Translated from Journal of Southeast University (Natural Science Edition), 2006, 36(5): 690–694 [译 自: 东南大学学报(自然科学版)]     

Error-space estimate method for generalized synergic target tracking

To improve the tracking accuracy and stability of an optic-electronic target tracking system, the concept of generalized synergic target and an algorithm named error-space estimate method is presented. In this algorithm, the motion of target is described by guide data and guide errors, and then the maneuver of the target is separated into guide data and guide errors to reduce the maneuver level. Then state estimate is implemented in target state-space and error-space respectively, and the prediction data of target position are acquired by synthesizing the filtering data from target state-space according to kinematic model and the prediction data from errorspace according to guide error model. Differing from typical multi-model method, the kinematic and guide error models work concurrently rather than switch between models. Experiment results show that the performance of the algorithm is better than Kalman filter and strong tracking filter at the same maneuver level. __________ Translated from Journal of University of Electronic Science and Technology of China, 2007, 36(2): 217–219 [译自: 电子科技大学学报]     

High-speed ground moving target detection research using triangular modulation FMCW

The frequency modulated continuous wave (FMCW) radar has the characteristics of low probability of interception, good hidden property and the ability to counter anti-radiation missiles. This paper proposes a new method for high-speed ground moving target detection (GMTD) using triangular modulation FMCW. According to the characteristic of the opposite range shift induced by the upslope and downslope modulation FMCW, the upslope and downslope are imaged, respectively. After compensation of continuous motion of the platform and time difference between upslope and downslope signals for imaging, the moving target can be detected through displaced phase center antenna (DPCA) technology. When the moving target is detected, the moving target image is extracted, and correlation processing is used to obtain the range shift, which can be used to estimate the target radial velocity, and further to find the real position of the target. The effectiveness of this method is verified by the result of computer simulation. __________ Translated from Journal of Xidian University, 2008, 35(4): 586–591 [译自: 西安电子科技大学学报(自然科学版)]     

Analytical design of PI controller for AQM with robustness adjustability

Based on a linearized TCP/AQMmodel, a new proportional integral (PI) controller design approach is proposed. This analytical approach applies H _∞ optimization and internal model control (IMC) theory to design active queue management (AQM) routers that support transmission control protocol (TCP) flows. The most important feature of the proposed scheme lies in that it can be explicitly tuned with a single parameter for the trade-off between performance and stability of the AQM control system. It is thus flexible and easy to use in design. The proposed method and the designed PI controller are verified and compared with other existing AQM schemes using ns-2 simulator. The results show the advantages of the new PI controller design approach for AQM routers supporting TCP flows. __________ Translated from Journal of Shanghai Jiaotong University, 2007, 41(5): 788–791 [译自: 上海交通大学学报]     

Common-mode radiation characteristic analysis of connections between cables and metal cases

In this paper, the common-mode radiation characteristic of the connection between a cable and a conductor is analyzed by the electric field integral function (EFIF) and the method of moment (MoM). The RWG basis function is adopted as the conductor basis function, the pulse basis function as the wire basis function and the juncture employs Costa basis function. A scheme of singular region separation is proposed to overcome the integration singularity of juncture matrix elements. Some new conclusions of the common-mode radiation characteristics with the metal case are obtained by numeration. __________ Translated from Chinese Journal of Radio Science, 2007, 22(3): 375–379 [译自: 电波科学学报]     

Medical image lossless compression based on combining an integer wavelet transform with DPCM

To improve the classical lossless compression of low efficiency, a method of image lossless compression with high efficiency is presented. Its theory and the algorithm implementation are introduced. The basic approach of medical image lossless compression is then briefly described. After analyzing and implementing differential plus code modulation (DPCM) in lossless compression, a new method of combining an integer wavelet transform with DPCM to compress medical images is discussed. The analysis and simulation results show that this new method is simpler and useful. Moreover, it has high compression ratio in medical image lossless compression. __________ Translated from Journal of Northeastern University (Natural Science), 2007, 28(10): 1454–1457 [译自 : 东北大学学报 (自然科学版)]     

Study and simulation of video communications under wireless environment based on blind source separation

A new scheme is proposed to separate several compressed video signals transferred in multiple wireless channels using the blind source separation method. The scheme selects IEEE 802.11b and XVID compression as the wireless communications channel and MPEG-4 video compression, respectively. A simulation model is then made for the video communications under a wireless environment. The model can separate several video signals using blind source separation. Simulations show that the normalized whiten plus cyclic whiten based on cyclostationary (NWCW-CS) algorithm based upon the cyclostationary characteristics of signals has the best separation performance and fast convergence. Besides, the algorithm can solve the mixing of video signals. The image of the transferred video signals decompressed by XVID is nearly consistent with the source ones. The new method meets the requirement of real-time video communications. __________ Translated from Journal of Southeast University (Natural Science Edition), 2007, 37(1): 13–17 [译自: 东南大学学报(自然科学版)]     

Blind source separation algorithm for communication complex signals in communication reconnaissance

Most blind source separation algorithms are only applicable to real signals, while in communication reconnaissance processed signals are complex. To solve this problem, a blind source separation algorithm for communication complex signals is deduced, which is obtained by adopting the Kullback-Leibler divergence to measure the signals’ independence. On the other hand, the performance of natural gradient is better than that of stochastic gradient, thus the natural gradient of the cost function is used to optimize the algorithm. According to the conclusion that the signal’s mixing matrix after whitening is orthogonal, we deduce the iterative algorithm by constraining the separating matrix to an orthogonal matrix. Simulation results show that this algorithm can efficiently separate the source signals even in noise circumstances. __________ Translated from Journal of Huazhong University of Science and Technology (Natural Science Edition), 2007, 35(4): 33–36 [译自: 华中科技大学学报(自然科学版)]