Table of Content

20 August 2013 Volume 40 Issue 4

  

Original Articles

Novel initial ranging method in the MIMO-OFDMA system

REN Guangliang;REN Xiaona

J4. 2013, 40(4):  1-5+41.  doi:10.3969/j.issn.1001-2400.2013.04.001

Abstract ( 1173 )   PDF (519KB) ( 1032 )   Save

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According to the feature of multiple antennas at the base station in the MIMO-OFDMA system, a novel initial ranging (IR) method exploiting the beamforming technique is proposed. The beamforming vector of the ranging signal is obtained by searching from the received signal vector of the multiple antennas. The signals received  by multiple antennas are combined by the beamforming vector, and the inter-user interference is suppressed. The combined signals are used in the multiuser detection and timing offsets estimation in the initial ranging. Simulation results show that the miss detection probability and false alarm probability of the multiuser detection by the proposed method are efficiently reduced, and that the performance of parameter estimation by the proposed method is better than that by the available methods.

Multiple watermarking framework of video content oriented AVS

TONG Ming;WU Yangcheng;ZHANG Jianlong;LUAN Yingzi

J4. 2013, 40(4):  6-13.  doi:10.3969/j.issn.1001-2400.2013.04.002

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Firstly, a non-negative matrix factorization with sparseness constraints on the parts (NMFSCP) method is proposed, which is used to extract the video movement component. The AC energy coefficients of DCT transformation are used as the texture feature simultaneously. Then the linear combination of two video features above is used to adjust the location and strength of the watermark adaptively. Secondly, one dynamic robust watermark and two fragile watermarks are generated according to the energy of the I-frame macro-block, which are used to detect and restore the attack position respectively. Finally, the robust watermark and two fragile watermarks are embedded into the medium and high frequency DCT coefficients which are the biggest of the luminance blocks in the I-frame respectively. Simulation results show that the embedded robust watermark is robust not only to general attacks but also to video special attacks, and that the mixture recovery detection mechanism based on two types of fragile watermarking is sensitive to tamper, has good accuracy of tamper localization and can recover the video frame location under the time-resynchronization attacks. The video stream need not be decoded completely for watermark extraction in this paper, so it meets the needs of real-time detection.

Joint pilot and soft information assisted carrier synchronization for short burst SOQPSK signals

SUN Jinhua;ZHU Jili;WU Xiaojun

J4. 2013, 40(4):  14-20+101.  doi:10.3969/j.issn.1001-2400.2013.04.003

Abstract ( 1126 )   PDF (953KB) ( 788 )   Save

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To solve the carrier recovery problem with large frequency offset in short burst communication systems using shaped-offset quadrature phase shift keying(SOQPSK), a joint pilot and demodulation soft information assisted carrier synchronization algorithm is proposed. First, coarse synchronization based on a few short pilot sequences is carried out. Then, further fine search is done around the coarse synchronization estimation region. The precise carrier synchronization parameters are obtained based on the maximum-mean-square soft output of SOQPSK. Simulation results show that at E_b/N₀≥0dB the proposed algorithm can eliminate large carrier offsets by as much as half the symbol rate, resist phase confusion and achieve effective carrier synchronization with 30 pilot bits and low computation complexity, achieving a BER performance which is very near the optimal coherent demodulation performance. When BER is in the region of 10^-2～10^-5, SNR degradation is below 0.3dB.

Frequency scaling algorithm for high squint FMCW-SAR imaging

LI Dong;LIAO Guisheng;YANG Zhiwei;XU Qing

J4. 2013, 40(4):  21-28. 

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For the invalidation of the present frequency scaling algorithm in the case of the high squint angle, a modified frequency scaling algorithm for high squint Frequency Modulated Continuous Wave Synthesis Aperture Radar imaging is presented. Based on the new Residual Video Phase (RVP), this algorithm can solve the problem of range frequency aliasing on the high squint mode effectively by considering the effect of the variation of the squint angle on the range bandwidth. Hence, high quality imaging can be obtained in the case of the high squint mode with the frequency scaling algorithm. Finally, performance analyses and simulation results demonstrate the effectiveness of the proposed algorithm.

New acquisition scheme with high sensitivity for long code

LI Wengang;HUANG Xinlei;LIU Longwei

J4. 2013, 40(4):  29-36.  doi:10.3969/j.issn.1001-2400.2013.04.005

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Focusing on the problem of low acquisition probability in the weak Satellite Navigation Position Systems signals environment, we propose an algorithm which can improve its acquisition signal-to-noise ratio (SNR) with multiple codes accumulation. The algorithm realizes codes coherent and incoherent accumulation by multiplexing the PMF-FFT(Partial Matched Filtering-Fast Fourier Transform)cell, which can lead to a longer accumulation time and more coherent accumulation gain. Thus, it increases the capture sensitivity, shortens the capture time, and reduces the interference. Simulation shows that the algorithm in this paper can obviously improve the system's capture performance. It is better than the conventional PMF-FFT algorithm by close to 4dB under the same SNR. The algorithm can be applied to the capture design in the second generation of COMPASS Navigation Satellite System.

L¹-norm method for multi-baseline InSAR phase unwrapping

YU Hanwen;BAO Zheng

J4. 2013, 40(4):  37-41.  doi:10.3969/j.issn.1001-2400.2013.04.006

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Multi-baseline phase unwrapping is a critical processing procedure of multi-baseline synthetic aperture radar interferometry (InSAR). However, it has a disadvantage that it is not robust to noise. In order to solve this problem, in this paper, an L¹-norm based single-baseline phase unwrapping method is proposed. By using the L¹-norm optimization model, the relation among interferograms obtained by multi-baseline InSAR is combined in the conventional signle-baseline L¹-norm phase unwrapping optimization model with this algorithm. Finally, simulated experiments demonstrate that this method has a better accuracy on phase unwrapping results and that it can be applied to measuring the complex terrain.

Integration of unicast and multicast scheduling with low complexity

JIANG Yongbo;YANG Chun;GAO Ya;QIU Zhiliang

J4. 2013, 40(4):  42-47.  doi:10.3969/j.issn.1001-2400.2013.04.007

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This study focuses on the scalability problems for very large, high-speed switches, and presents a two-stage integrated scheduling algorithm named UMCSA(Unicast and Multicast Concurrent Scheduling Algorithm)which supports both unicast and multicast traffic simultaneously. The first stage of the switching fabric performs switching for unicast traffic and load-balancing for multicast traffic, while the second stage performs switching for load-balanced multicast traffic. With a two-phase(request-grant)scheme, the proposed algorithm performs without iteration, and at the same time reduces the scheduling overhead to O(logN) significantly. By using the VOQ(Virtual Output Queuing)technique for unicast and multicast traffic separately at different stages, the HoL(Head-of-Line)blocking is eliminated and therefore a good throughput performance could be achieved. UMCSA performs scheduling for unicast and multicast traffic in parallel at different stages with simple Round-Robin arbitration, which is more suitable for high-speed applications. Simulation results show that the proposed integrated algorithm exhibits a good performance in terms of throughput and average delay, at different traffic compositions under various traffic patterns.

Heterogeneous Markov chain model of the target existence variable for Bayesian track-before-detect

XIA Shuangzhi;YAN Junkun;DAI Fengzhou;LIU Hongwei

J4. 2013, 40(4):  48-55.  doi:10.3969/j.issn.1001-2400.2013.04.008

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In order to improve the detection performance of Bayesian track-before-detect, this paper proposes a heterogeneous Markov chain model for target existence variable. In the proposed model, the transition probability of the target existence variable is related with the posterior probability of target existence at the current time, which is more consistent with the transitions of target existence variable. Simulation results show that the detection performance can be improved by the proposed heterogeneous model compared with the traditional homogeneous model.

New homogenized-feature-based multi-spectral image registration method

WU Chenyang;NIU Haijun;CHI Xuyan

J4. 2013, 40(4):  56-59.  doi:10.3969/j.issn.1001-2400.2013.04.009

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A study aiming to achieve both the speed and accuracy of feature based multi-spectral image registration process is made. Then a new homogenized feature based image registration method is proposed. The method first uses the DOH operator to detect features, and then a circular filter window is used to adaptively select features based on the spatial distribution and intensity while keeping the features' rotation invariance. The selected features are further described and matched. Experiments show that the selected features are more robust and more uniformly distributed and that the method has great advantages in both speed and accuracy.

Multiuser iterative precoding algorithm based on the matching weighted signal-to-leakage-and-noise ratio

SUN Chuiqiang;GE Jianhua;ZHU Bin;LI Jing

J4. 2013, 40(4):  60-64.  doi:10.3969/j.issn.1001-2400.2013.04.010

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A multiuser iterative precoding algorithm is proposed to reduce the multiuser interference in multiple antenna cellular communication systems. The proposed algorithm is based on the matching weighted signal-to-leakage-and-noise ratio. In the proposed algorithm, the effective channel gain of each user is selected as the matching weighted factor, and the leakage power received by each user is weighted by the factor. An exact closed form solution for the precoding vector is obtained by maximizing the matching weighted signal-to-leakage-and-noise ratio, and then optimized by using an iterative optimization approach. Simulation results show that the proposed iterative algorithm based on the matching weighted signal-to-leakage-and-noise ratio can improve the sum capacity of the system, and retain low computational complexity.

Ambiguity function of the ground-satellite bistatic SAR system

LIU Xin;ZHANG Linrang;LIU Nan

J4. 2013, 40(4):  65-71.  doi:10.3969/j.issn.1001-2400.2013.04.011

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Base on the earth, moon and satellite trajectories, the geometric model of ground-satellite SAR is presented. The ambiguity function of ground- satellites bistatic SAR is defined and the ambiguity function formula is derived. Moreover, we analyzed the ambiguity function of ground-satellite SAR through numerical simulation. The simulation results demonstrate the validity of proposed function. Furthermore, it is the theoretical basis for the subsequent research on the imaging algorithm.

Orthogonal optimal design and analysis of RPCVD simulation by CFD

DAI Xianying;GUO Jingjing;SHAO Chenfeng;ZHENG Ruochuan;HAO Yue

J4. 2013, 40(4):  72-78.  doi:10.3969/j.issn.1001-2400.2013.04.012

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The simulation of multi-level and multi-factor for the growth of SiGe matetial by RPCVD is designed by adopting the orthogonal method. A FLUENT simulation of density, velocity and pressure distributions for the above designs is given by using CFD software. According to the range and variance analysis of the growth surface simulation results in nine positions, the final optimized simulation parameters are obtained. The optimization results by using the Orthogonal Method that the flux of the inlet is 1.67×10^-4m³/s, the pressure of the chamber is 2666.44Pa at low tempreture(823K) and  that the flux keeps 1.67×10^-4m³/s, and the pressure is 7999.32Pa at high tempreture(1123K) are consistent with those by practical technology.

Beamforming assisted successive interference cancellation initial ranging algorithm for OFDMA systems

XIA Yujie;REN Guangliang

J4. 2013, 40(4):  79-84+154.  doi:10.3969/j.issn.1001-2400.2013.04.013

Abstract ( 1092 )   PDF (569KB) ( 766 )   Save

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According to the effect of the frequency selectivity of multipath channel and multiuser access interference (MAI) on the initial ranging system in the orthogonal frequency division multiple access (OFDMA) network, a novel beamforming assisted successive interference cancellation initial ranging algorithm is presented by utilizing smart antennas at the base station in the next generation wireless communication systems. In the algorithm, the cell is divided into many small ranging sectors in the spatial domain by a group of beamforming vectors. The proposed algorithm is able to improve the signal-to-interference-plus-noise ratio of the desired ranging users in a given sector and suppress the MAI from other ranging sectors. In the small ranging sector, the multiuser ranging code detection and timing offset estimation are conducted by the simplified successive multiuser detection and interference cancellation (SMUD) method and the adaptive threshold. Simulation results show that the correct detection probability of the proposed algorithm is improved by 80％ than that of the SMUD algorithm, with 15 ranging users in the ranging channel when the SNR is -6dB.

Adaptive iteration Fourier technique applied for antenna arrays pattern synthesis

WANG Xinkuan;JIAO Yongchang;TAN Yanyan

J4. 2013, 40(4):  85-89+187.  doi:10.3969/j.issn.1001-2400.2013.04.014

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Based on the existing method of iterative Fourier transforms, an adaptive iteration Fourier technique (AIFT) is proposed for antenna arrays synthesis. Compared with the initial method, three different aspects exist in AIFT. Firstly, the method could adaptively compute the peak sidelobe threshold(PST) in order to obtain the optimum distribution of element excitations satisfying the objective parameter. Secondly, un-uniform element excitations are employed to meet the requirement of sidelobe reduction. Thirdly, when the antenna arrays were massively truncated, the method could lower the beamwidth of their far field patterns by adaptively modulating the value of array factors that are located in the edge region of mainlobes so that the beam broadening caused by the initial method could be efficiently avoided. Simulation results for different design requirements show the effectiveness and high efficiency of the proposed method.

Estimation of the X-ray pulsar signal based on the Bayesian multiscale model

LIU Xiuping;LI Xiaoping;SUN Haifeng;FANG Haiyan

J4. 2013, 40(4):  90-95.  doi:10.3969/j.issn.1001-2400.2013.04.015

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To extract the X-ray pulsar signal buried in the strong noise, an estimation method based on the Bayesian multiscale model is proposed. The X-ray pulsar signal is modeled according to the Poisson process. The algorithm is used to decompose the signal into multiscale trees using Recursive Dyadic Partitions. The signal intensity is modeled by the characteristic of independent Poisson random variance. Under the squared-error loss function, the estimator is obtained by computing the posterior estimation. The performance of the algorithm is investigated through real-data from RXTE. The effectiveness and applicability of the proposed approach are demonstrated.

Reverse dispatching scheme for satellite Clos-network switches

ZHANG Maosen;QIU Zhiliang;GAO Ya;LI Jun

J4. 2013, 40(4):  96-101.  doi:10.3969/j.issn.1001-2400.2013.04.016

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For the special requirements of the on-board switching for satellite communication on hardware complexity and matching efficiency, the reverse dispatching scheme for MSM Clos-network switches is proposed. Unlike the previous dispatching schemes which perform matching according to the order of modules, the reverse dispatching scheme first buffers requests, and then performs internal matching in central modules instead. Then the results of the matching are used for the cell-sending in input modules. Different steps of the whole dispatching scheme are isolated in this dispatching scheme, which means that the performance of a step does not depend on the result of the preceding one. Then the whole dispatching scheme can be performed in a pipelined manner. Simulation results show that the reverse dispatching scheme can improve the dispatching efficiency without additional hardware overhead and achieve a low end-to-end delay.

Novel cyclic energy spectrum detection method for deep space communications

REN Guangliang;MIN Quanyun;LU Manhong

J4. 2013, 40(4):  102-107.  doi:10.3969/j.issn.1001-2400.2013.04.017

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According to the extremely low signal-to-noise ratio (SNR) of the received signal and the large Doppler frequency shift in the deep space communication systems, a novel detection method based on the cyclic energy spectrum is proposed. Firstly, the distribution of energy of the cycle frequency slices in the cyclic spectrum is defined as the cyclic energy spectrum. Then we correlate the cyclic energy spectrum of the received signal with that of the transmitted signal as the detecting statistic, which can determine whether the signal is present or not. Simulation results show that the proposed detector can obtain a gain under an SNR of more than 6.5dB compared with the existing detectors, and is robust to the Doppler frequency shift.

Change detection in multi-temporal remote sensing images based on the wavelet-domain immune clonal optimazition

WANG Lingxia;JIAO Licheng;YAN Xueying;XIN Fangfang

J4. 2013, 40(4):  108-113.  doi:10.3969/j.issn.1001-2400.2013.04.018

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In order to reduce the impact of noises on detection accuracy in change detection for remote sensing images, a novel change detection method is proposed based on the immune clone algorithm and wavelet transform. Firstly, the multi-scale and low-pass smoothing characteristics of wavelet transform are utilized to construct multi-layered difference images. Secondly the time domain deviations caused by operation of zero insertion and image convolution in wavelet transform are corrected by the immune clonal algorithm that the initial segmentation results obtained using the Rayleigh-Gauss model are matched by the secondary linear interpolation operation. Finally, the change detection is accomplished by image fusion. Simulation results show that the algorithm can not only reduce the image noises, but also suppress the image deviations caused by wavelet transform effectively. The accuracy of change detection is improved significantly.

Phase noise measurement based on the regularity change of phase difference group

LI Zhiqi;ZHOU Wei;ZHANG Xueping;LIU Chen

J4. 2013, 40(4):  114-118.  doi:10.3969/j.issn.1001-2400.2013.04.019

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A method for phase noise measurement is put forward based on the regularity change of the phase difference group and the frequency relationship between the signals. The technology takes advantage of the phase difference relationship affected phase fluctuant change between the periodic signals in nature. The ± 1 count error can be eliminated by building the measuring gate using phase coincidence detection to measure phase difference group synchronization between reference and measured frequency. The comparison and processing can be completed between the same or multiple frequency signals. The phase noise measurement can be realized in this condition so that the carrier frequency is inhibited in order to extract the information on the signal phase noise. The high resolution phase measurement can be realized in the frequency range of 1～190MHz.

Corner detection via anisotropic Gaussian kernels information entropy on edge contours

ZHANG Weichuan;SHUI Penglang;XU Guojing

J4. 2013, 40(4):  119-124+129.  doi:10.3969/j.issn.1001-2400.2013.04.020

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To improve the accuracy of corner detection, a new corner detector is proposed based upon the information entropy which is derived by the anisotropic Gaussian directional derivatives (ANDDs) on edge contours of an image. Firstly, the edge map of an image is extracted by the Canny edge detector. Secondly, small gaps between contours are filled. Finally, on each contour pixel, the main direction corresponding to the maximal ANDDs at each contour pixel and its surrounding pixels are used to compute the main direction's probability density function and information entropy. Different from the traditional contour-based detectors, our detector uses the maximal intensity variation's directional information entropy on contours and surrounding pixels rather than the curvatures of the planar curves, which presents better robustness. Experimental results show that the proposed detector achieves a better corner detection performance than several state-of-the-art detectors.

Design of the satellite synchronized clock

XUAN Zongqiang;SUN Xiaoli;LIU Chen;KANG Jingjing

J4. 2013, 40(4):  125-129.  doi:10.3969/j.issn.1001-2400.2013.04.021

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This paper introduces a system for a new type of GPS/the Beidou locking second-class frequency standard of measuring time intervals based on the TDC-GP2 Chip. It also presents the overall design scheme for the system, develops the hardware and software frame, and implements the Kalman filter algorithm combined with the method of linear average for estimating and filtering noise. The universal TDC-GP2 produced by the ACAM company for measuring time interval of locked second-class frequency standard system is used by the satellite. By increasing another dividing frequency output signal 1PPS2, the measurement range is extended to -3.25～+3.25ms and the time resolution of 50ps is obtained. Experimental results show that the system's locked output frequency accuracy is as high as 10^-12(24-hour average). Frequency stability is better than 10^-11/s. Compared with the traditional frequency standard locked system, the system has the advantages of simple circuit, convenient adjustment, wide measurement range, small additional noise, and high precision.

Design of a trimmed current reference with a low temperature drift

TANG Hualian;ZHUANG Yiqi;ZHANG Li;JING Xin;DU Yongqian

J4. 2013, 40(4):  130-136.  doi:10.3969/j.issn.1001-2400.2013.04.022

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Component tolerances and mismatches due to process variations severely degrade the performance of bandgap reference circuits. Based on device mismatch models, a current reference I_ref with adjustable output current from 15μA to 80μA is designed. A compensated circuit is used to reduce the temperature drift. To achieve more accurate current reference, an 8bit bi-directional trimming array with 127 current levels is proposed. This digitally programmable array is binary weighted for accuracy and flexibility. Simulation shows that the temperature coefficient is 26ppm/℃ over the wide range of -40℃ to 120℃when the output current is 15μA. Based on the CMOS 0.13μm technology, the measurement results show that the trimmed range and precision for current reference are -14.3％·I_ref～14.3％·I_ref and 0.11％·I_ref, respectively. The circuit could be applied to high precision A/D and D/A converters.

Organizational evolutionary algorithm for occlusion recovery

PENG Yali;LIU Fang

J4. 2013, 40(4):  137-141.  doi:10.3969/j.issn.1001-2400.2013.04.023

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To effectively recover the occlusion real position, an organizational evolutionary algorithm for occlusion recovery is presented in this paper. The occlusions are regarded as the variants and the objective function is obtained based on the property that the rank of the matrix consists of all the image points is 4. And the value searched by organizational evolutionary is taken as the occlusion position. The individual of population is evaluated by the objective function. After several generations, the best individual is regarded as the occlusion position. The algorithm does not need the initial value and treats all the images and image points uniformly. Simulation and real data show that the algorithm can efficiently recover the occlusion.

Research on biomimetic pattern recognition for object adaptive tracking algorithm

LIU Huanyun;WANG Junning;HE Di;TU Shangbin

J4. 2013, 40(4):  142-148.  doi:10.3969/j.issn.1001-2400.2013.04.024

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A new method for image object recognition and tracking based on Biomimetic Pattern Recognition (BPR), which can automatically change the size of the object, is proposed. To accomplish the learning process of the sample objects with different sizes, an artificial neural network model is used to cover the training sample. The curve fitting method based on the Radial Basis Function (RBF) neural network is presented to approximate the size of the objects in the coverage of the network formed by BPR theory in order to change the size of the object automatically. The Quadratic Minimum Distance algorithm based on the Euclidean distance is applied to search the target in the process of object recognition and tracking. Experimental results and theoretical analysis show that the algorithm proposed in this paper is more effective and robust in object recognition and tracking of video image sequences than the BP neural network.

Adaptive bit partition algorithm in cooperative distributed antenna systems

GUI Xin;KANG Guixia;ZHANG Ping

J4. 2013, 40(4):  149-154.  doi:10.3969/j.issn.1001-2400.2013.04.025

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This paper proposes a new limited feedback bit partition algorithm to minimize the rate loss caused by the channel quantization error, based on the cooperative distributed antenna system (DAS). There are two kinds of interferences in multi-user cooperative DAS: multi-user interference (MUI) within the local cell and inter-cell interference (ICI) from adjacent cells. To suppress these two kinds of interferences, this paper uses the random vector quantization (RVQ) codebook to separately quantize the channel state information (CSI) from the local cell and adjacent cells. Under the condition that uses' total feedback overhead is fixed, we use a two-step optimization method to obtain the optimal solution of the feedback bit number allocated to local and adjacent cells. Simulation results show that the proposed algorithm effectively increases the average transmission rate compared with the equal-bit partition algorithm.

New smart noise jamming of radar signal frequency modulation

GUO Junjie;WANG Xinghua;WANG Xing;SI Jianhua;ZHANG Wenxia

J4. 2013, 40(4):  155-160.  doi:10.3969/j.issn.1001-2400.2013.04.026

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A new frequency modulation smart noise jamming technique is proposed against the radar linear frequency modulation(LFM) signal and pulse compression processing.The jamming signal is acquired by modulating the received radar signal frequency with gause white noise.It can produce frequency domain deceptive jamming and Doppler frequency narrowband noise jamming according to the gause white noise bandwidth.This smart noise jamming signal has much correlation with the radar signal, can get a high pulse compression gain after matched filtering and raising the jamming power efficiency.

Research on the recognition algorithm of Turbo codes on  trellis termination

LI Xiaotian;ZHANG Runsheng;LI Yanbin

J4. 2013, 40(4):  161-166.  doi:10.3969/j.issn.1001-2400.2013.04.027

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For the blind recognition of Turbo codes in information interception, the recognition algorithm of turbo codes on trellis termination fall into following two parts. In coding structure recognition, turbo codes on trellis termination is defined as linear block codes, so the blind recognition of code length and start is achieved by analyzing the rank of codes matrix with a different number of columns and a different start; In encoder parameter recognition, by comparing the sequence matrix's column vector before and after interleaving and determining the decision threshold, the influence of error codes whose number is lower than the decision threshold is removed, and consequently, the problem of poor fault-tolerant performance in the traditional interleaving mode recognition method is solved. Simulation shows that the correct percentage of recognition is higher than 80％ at 10^-3 BER, and confirms the validity and reliability of the algorithm.

Blind semi-definite programming sequence detection of the 4PAM/16QAM signal in the SIMO system

XUE Jiang;PENG Hua;MA Jinjin

J4. 2013, 40(4):  167-173+196.  doi:10.3969/j.issn.1001-2400.2013.04.028

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Direct blind sequence detection of the 4PAM/16QAM signal based on semi-definite programming (SDP) for the Single-Input-Multiple-Output (SIMO) system is proposed. In the process of blind SDP detection, firstly we relax the signal blind detection problem in such a way that the relaxed SDP problem is easier to solve; then we solve the SDP problem; thirdly we use randomization strategy to convert the SDP solution to the original blind signal detection problem. The SDP blind detection problem does not depend explicitly or implicitly on the channel order, nor needs the assumption that the parallel channels should be coprime, so it has extensive applicability. Simulation shows that the proposed algorithm demonstrates the advantage of a fast convergence rate and complete independence of channel order estimation and coprime assumption.

QoS-aware temporal prediction model for personalized service recommendation

PENG Fei;DENG Haojiang;LIU Lei

J4. 2013, 40(4):  174-180.  doi:10.3969/j.issn.1001-2400.2013.04.029

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An optimized temporal prediction model for quality of service (QoS) is proposed to improve the prediction accuracy of personalized service recommendation. A baseline model is proposed to transform the prediction task from overall value prediction to bias value prediction, and combined with the matrix factorization technique to build the baseline matrix factorization (BMF) model. Matrix factorization models are designed to denote the time effect of both client and server sides, and then integrated with the BMF model to build the temporal baseline matrix factorization (TBMF) model. Experimental results show that, compared with the existing temporal prediction model for QoS, the BMF model can improve the precision substantially, and that the TBMF model can be improved further.

Propagator method for multiple-parameter estimation of LFM signal for conformal array antenna

ZHANG Shuyin;GUO Ying;QI Zisen;HUO Wenjun

J4. 2013, 40(4):  181-187.  doi:10.3969/j.issn.1001-2400.2013.04.030

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A multiple parameter estimation method for the LFM signal for the conformal array antenna is presented. By employing the energy focusing property of certain-ordered-FRFT to the LFM signal, multiple components blended in received data are separated in the FRFT domain, and hence the simplified data model is acquired, because of which the complicated parameter match is avoided, and then the DOA and polarization estimation is performed by using the PM algorithm. Benefiting from the avoiding of parameter matching and high dimensional eigen-value decomposition, the complexity and computational burden of the algorithm is remarkably controlled. Simulation results show that the proposed algorithm has an approximate performance with a much lower computation burden than ESPRIT.

Motion compensation approach for wide-swath missile-borne SAR imagery

BAO Min;ZHOU Song;SHI Lin;WEN Jun

J4. 2013, 40(4):  188-196.  doi:10.3969/j.issn.1001-2400.2013.04.031

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In wide-swath missile-borne synthetic aperture radar (SAR) imaging, the range-variant residual phase modulation, which is introduced by the presence of trajectory deviations, will seriously degrade the focusing quality of the final image. To deal with this problem, a motion compensation approach for missile-borne SAR is proposed. In the approach, the signal model of motion error for diving movement is established. Then, according to the inertial navigation system (INS) information, the range-variant residual Doppler rates of the echoes are extracted by using the Doppler rate estimation, on the basis of which the corresponding phase error can be calculated and compensated. Simulation results show that, by using the proposed approach, the influences of the motion error on focusing are greatly reduced with the well focused image obtained.