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Target searching based on modified implicit ROI encoding scheme

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Journal of Systems Engineering and Electronics 2008年第5期19卷 888-892页

作者： Bai Xu zhang zhongzhao Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

An EBCOT-based method is proposed to reduce the priority of background coefficients in the ROI code block without compromising algorithm complexity. The region of interest is encoded to a higher quality level than background, and the target searching time in video-guided penetrating missile can be shortened. Three kinds of coding schemes based on EBCOT are discussed. Experimental results demonstrate that the proposed method shows higher compression efficiency, lower complexity, and good reconstructed ROI image quality in the lower channel capacity.

关键词： video-guided penetrating bomb implicit ROI EBCOT.

Resource allocation with CCI suppression for multiuser MIMO-OFDM downlink in correlated channels

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Journal of Systems Engineering and Electronics 2008年第2期19卷 213-219页

作者： zhang Chengwen zhang zhongzhao Ma Yongkui Communication Research Center Harbin Inst. of Technology Harbin 150080 P. R. China

To minimize the overall transmit power while maintaining a constant data rate and target BER, a downlink adaptive resource allocation algorithm with jointing the exclusive manner and the shared manner is proposed for multiuser MIMO-OFDM system in correlated channels. The algorithm allocates all the subcarriers to different users according to their spatial correlations. The users with high spatial correlation are allocated in the same group and the exclusive manner is applied. The shared manner with an improved null broadening method, which improves the performance of co-channel interference （CCI） suppression and decreases the number of transmit antennas required, is applied between the different group users. As the user＇s direction of departure （DOD） changes very slowly, a looking up table method is used to reduce the computational complexity. The simulation results show that despite the angle spread of DOD, when compared with the exclusive manner, the proposed algorithm improves the spectral efficiency, and when compared with the TDMA-ZF （zero forcing） shared manner, the proposed algorithm decreases the total transmit power by at least 1 dB.

关键词： resource allocation MIMO-OFDM multiuser CCI suppression zero forcing null broadening.

Optimal antenna placement in distributed antenna systems

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Journal of Systems Engineering and Electronics 2012年第4期23卷 467-472页

作者： zhongzhao zhang Zhun Ye Weilin Jiang School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150080R R.China

To minimize the outage probability of the cell （OPC） in downlink distributed antenna systems with selection transmission, a complex-encoding genetic algorithm （GA） is proposed to find the optimal locations of the antenna elements （AEs）. First, the outage probability at a fixed location in the cell is investigated. Next, an analytical expression of the OPC is derived, which is a function of the AE locations. Then the OPC is used as the objective function of the antenna placement optimization problem, and the complex- encoding GA is used to find the optimal AE locations in the cell. Numerical results show that the optimal AE locations are symmetric about the cell center, and the outage probability contours are also given with the optimal antenna placement. The algorithm has a good convergence and can also be used to determine the number of AEs which should be installed in order to satisfy the certain OPC value. Lastly, verification of the OPC＇s analytical expression is carried out by Monte Carlo simulations. The OPC with optimal AE locations is about 10% lower than the values with completely random located AEs.

关键词： distributed antenna system (DAS) outage probability,genetic algorithm (GA).

Radio map updated method based on subscriber locations in indoor WLAN localization

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Journal of Systems Engineering and Electronics 2015年第6期26卷 1202-1209页

作者： Ying Xia zhongzhao zhang Lin Ma School of Electronics and Information Engineering Harbin Institute of Technology School of Communication and Electronic Engineering Qiqihar University

With the rapid development of wireless local area network （WLAN） technology, an important target of indoor positioning systems is to improve the positioning accuracy while reducing the online calibration effort to overcome signal time-varying. A novel fingerprint positioning algorithm, known as the adaptive radio map with updated method based on hidden Markov model （HMM）, is proposed. It is shown that by using a collection of user traces that can be cheaply obtained, the proposed algorithm can take advantage of these data to update the labeled calibration data to further improve the position estimation accuracy. This algorithm is a combination of machine learning, information gain theory and fingerprinting. By collecting data and testing the algorithm in a realistic indoor WLAN environment, the experiment results indicate that, compared with the widely used K nearest neighbor algorithm, the proposed algorithm can improve the positioning accuracy while greatly reduce the calibration effort.

关键词： subscriber location wireless local area network(WLAN) positioning accuracy calibration effort hidden Markovmodel (HMM).

Resource allocation for multiuser STBC-BF MIMO-OFDM downlink with imperfect channel information

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Journal of Systems Engineering and Electronics 2009年第4期20卷 687-693页

作者： zhang Chengwen Liao Minghong zhang zhongzhao Meng Weixiao Communication Research Center Harbin Inst. of Technology Harbin 150080 P. R. China School of Computer Science and Technology Harbin Inst. of Technology Harbin 150001 P. R. China

To improve the performance of a multiuser MIMO-OFDM system with imperfect channel status information, a downlink adaptive resource allocation algorithm which combines space-time block coding and beam forming （STBC-BF） is proposed. The algorithm allocates the subcarriers with a shared manner. A zero forcing processing with joint Rx-Tx is used to suppress the co-channel interference （CCI） and to construct uncorrelated channels for STBC. An adaptive power allocation for the STBC equivalent channels can increase signal to interference and noise ratio at the receiver. Simulation results show that under the condition of an imperfect CSI, the proposed algorithm improves the system performance and reduces the number of BS transmit antennas required.

关键词： resource allocation MIMO-OFDM multiuser STBC-BF CCI suppression

Deterministic simulation of UWB indoor propagation channel

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Journal of Systems Engineering and Electronics 2008年第3期19卷 447-452页

作者： Wang Yang zhang Naitong zhang Qinyu zhang zhongzhao Communication Engineering Research Center Harbin Inst. of Technology Shenzhen Graduate School Shenzhen 518055 P. R. China Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

A site-specific model of UWB pulse propagation in indoor environment is addressed. The simulation utilizes the principles of geometrical optics （GO） for direct and reflected paths＇ tracing and the time domain technique for describing the transient electromagnetic field reflected from wall, floor, ceiling, and objects. The polarization of the received waveform is determined by taking into account the radiation pattern of the transmitting and receiving antennas, as well as the polarization changes owing to every reflection. The model provides more intrinsical interpretations for UWB pulse propagation in realistic indoor environment.

关键词： UWB time domain indoor propagation channel diffraction.

Characterizing Ultra-wide Band indoor line-of-sight wireless channel

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Journal of Systems Engineering and Electronics 2007年第4期18卷 673-678,697页

作者： Wang Yang zhang Naitong zhang Qinyu zhang zhongzhao Communication Research Center Harbin Institute of Technology Harbin 150001 P. R. China

By exploring the deterministic characteristics of the measurement data, a new propagation model with two deterministic clusters and stochastic arriving rays within each cluster is proposed. When considering the cumulative distribution function （CDF） of the three key channel statistics, the proposed model fits the measurement data better than SV/IEEE 802.15.3, a model which is known as a standard model for UWB indoor propagation channel. Therefore, with the additional knowledge of the specific environment geometry, the proposed model generating impulse responses ＂resemble＂ the measured channel impulse responses better than IEEE model. Moreover, the proposed model＇s parameters obtaining procedure is simplified by utilizing simple parameters of the environment.

关键词： UWB wireless channel propagation characteristic indoor channel.

Deconvolution techniques for characterizing indoor UWB wireless channel

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Journal of Systems Engineering and Electronics 2008年第4期19卷 688-693页

作者： Wang Yang zhang Naitong zhang Qinyu zhang zhongzhao Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

A deconvolution algorithm is proposed to account for the distortions of impulse shape introduced by propagation process. By finding the best correlation of the received waveform with the multiple templates, the number of multipath components is reduced as the result of eliminating the ＂phantom paths＂, and the captured energy increases. Moreover, it needs only a single reference measurement in real measurement environment （do not need the anechoic chamber）, which by far simplifies the templates acquiring procedure.

关键词： ultra-wide band channel model CLEAN algorithm CIR deconvolution.

Simplified calculation of UWB signal transmitting through a finitely conducting slab

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Journal of Systems Engineering and Electronics 2008年第6期19卷 1070-1075页

作者： Wang Yang zhang Naitong zhang Qinyu zhang zhongzhao Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

A simplified closed-form analytic solution for UWB impulse signal transmitting through a finitely conducting slab is proposed. The approach first requires evaluating the impulse response of the slab and then convolving it with the specified incident field waveform. To obtain the impulsive transmitting field, either for vertical or horizontal polarization, approximations to the refraction coefficients and propagation loss are made, which can be proved to be accurate enough, comparing with their frequency domain solutions. Thereby, it permits simplified closed-form expressions in the time domain for both terms. The resulting transient response for the transmitting impulse field is then given by convolution of the time domMn refraction coefficients and time domain propagation loss. A numerical example of an incident monocyele transmitting through a slab using this technique, is presented, to illustrate the effective use of the method.

关键词： ultra-wide band time domain indoor propagation channel multipath.