Table of Content

20 August 2011 Volume 38 Issue 4

  

Original Articles

Quantum multi-user self-adaptive adjusting detection scheme

ZHAO Nan;PEI Changxing;LIU Dan;SUN Xiaonan

J4. 2011, 38(4):  1-5+31.  doi:10.3969/j.issn.1001-2400.2011.04.001

Abstract ( 1502 )   PDF (494KB) ( 1181 )   Save

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For quantum communication, quantum multi-user detection must accomplish communication, so that quantum multi-user detection is a key point. In this paper, we note that the quantum multi-user detection differs from the classical one, construct a multi-user quantum communication channel model, and propose a new self-adaptive adjusting quantum detection scheme. This scheme is feasible and error rate is reduced by measuring the actual optical fiber channel.

Quantitative identification method for the ionizing radiation induced 1/f noise in MOSFETs

LI Weihua;DU Lei;BAO Junlin;MA Zhongfa

J4. 2011, 38(4):  6-10+48.  doi:10.3969/j.issn.1001-2400.2011.04.002

Abstract ( 1455 )   PDF (653KB) ( 1072 )   Save

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Wavelet maxima statistic analysis is applied to the low frequency noise of MOSFETs before and after ionizing radiation. It is found that the wavelet maxima statistics of the low frequency noise both from nMOSFETs and pMOSFETs are similar to the numerical signal generated by RTNs superposition. The discrepancy between the wavelet maxima statistics of nMOSFETs and that of pMOSFETs is quite trivial before ionizing radiation, whereas it becomes much more evident after radiation. Based on the wavelet maxima statistics analysis, it is concluded that the dominant low frequency noise generating mechanisms in both nMOSFETs and pMOSFETs are RTNs superposition. Ionizing radiation does not add new types of defects to the devices, but increase their density. nMOSFETs is damaged more severely than pMOSFETs during radiation.

Key-insulated component property-based attestation

SUO Yan;XU Xiaoyan;ZHANG Yusen;ZHANG Tao;GUI Jingjing;YANG Li;YUE Kang

J4. 2011, 38(4):  11-19.  doi:10.3969/j.issn.1001-2400.2011.04.003

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This paper applies the mechanism of Key-insulated security to the component property-based attestation and analyzes the correction and security of the scheme. The analysis shows that the component which has not been updated or attacked by the malicious code will lose the security property, and would not have the ability of remote attestation. This paper implements the certificateless component property based attestation, which eliminates the process of verifying the certificate, reduces the burden of the verifier, and gives the implementation process by combining with the existing integrity management model of trusted computing.

Joint resource management in multi-antenna cognitive radio networks

LI Zhao;ZHAO Linjing;LIU Qin

J4. 2011, 38(4):  20-25+37.  doi:10.3969/j.issn.1001-2400.2011.04.004

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This paper designs signal processing algorithms at transmitter and receiver ends jointly in multi-antenna cognitive radio networks. Accordingly the cognitive system could coexist with the primary in one occupied authorized frequency channel without interfering with the primary. Based on the algorithms we devise a spatio-temporal resource model, and then propose a joint resource management method. Simulation results show that compared with non-coexistent method, the proposed scheme could effectively improve the performance of the cognitive system on the premise that cognitive transmission imposes no interference on the primary.

Digital image stabilization algorithm applicable to large rotation

CHU Xiuqin;WANG Fei;NI Lezhen;LIU Yang

J4. 2011, 38(4):  26-31.  doi:10.3969/j.issn.1001-2400.2011.04.005

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Based on corner detection, a matching strategy featured point-to-multipoint is presented, from which it is proposed a new image stabilization algorithm for image sequences with both translation and large rotation. The algorithm has made a breakthrough to the limitations of both the traditional algorithms' capability of only resolving translation or small rotation(3° to 5° on average) and the necessity of the center of rotation being precisely determined. Experimental results show that the algorithm still effectively functions even when the rotation angle reaches18°. Also, the average PSNR is raised approximately 26dB after stabilization.

Dynamic spectrum allocation algorithm for heterogeneous radio networks based on reinforcement learning

ZHANG Wenzhu;SHAO Lina

J4. 2011, 38(4):  32-37.  doi:10.3969/j.issn.1001-2400.2011.04.006

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An adaptive heuristic critic (AHC) Reinforcement Learning algorithm is presented for the dynamic spectrum allocation in an autonomously deciding mode in heterogeneous radio networks based on the normalized radial basis function (NRBF). The algorithm accelerates the learning speed by utilizing the NRBF when constructing the state space, and improves the learning efficiency by using the AHC scheme to reduce the unnecessary exploration. Through interactions with the radio environment, it learns to allocate the proper frequency band for each session in multiple radio access networks. Simulation results show that the proposed algorithm can lead to a better spectrum efficiency and quality of service compared with to the fixed frequency planning scheme or general dynamic spectrum allocation policy.

Study of the Ohmic contact property of SiC

WANG Ping;YANG Yintang;GUO Lixin;SHANG Tao;LIU Zengji

J4. 2011, 38(4):  38-41.  doi:10.3969/j.issn.1001-2400.2011.04.007

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Multi-layer metal Ohmic contacts to 4H-SiC are investigated on the N⁺ion implanted layer with 950℃ annealing in Ar for 25 minutes and the n type epitaxial layer with a carrier concentration of 1.0×10¹⁹cm^-3 with 1000℃ annealing in N₂ for 2 minutes. The specific contact resistances obtained by the transmission line method (TLM) are 1.359×10^-5Ω·cm² and 3.44×10^-6Ω·cm², respectively. SIMS measurements show that the formation of the Ni silicide and the TiC facilitates to make the contacts become more Ohmic after annealing.

TDOA estimation of the overlapping signal of multiple chirps

LUO Yongjiang;ZHAO Guoqing;SI Haifei

J4. 2011, 38(4):  42-48.  doi:10.3969/j.issn.1001-2400.2011.04.008

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TDOA estimation of the overlapping signal of multiple chirps with atomic decomposition is studied, and the algorithm for the TDOA estimation of signals based on chirplet atomic decomposition is derived. Using chirplet atomic decomposition, the overlapping signal received directly from the master-receiver can be approached by some chirplet atom dictionary. And then we compute the correlation between each atom and overlapping signal from the slaver-receiver, and search for the peak of correlation. TDOA of every chirp between master-receiver and slave-receiver can be estimated. Simulation shows that the performance of this method is better than that of computing correlation only between signals received by the master-receiver and slave-receiver.

Motion vector prediction method for irregularly-shaped macroblock partition

LI Zhibin;CHANG Yilin;LIU Xiaoxian

J4. 2011, 38(4):  49-55.  doi:10.3969/j.issn.1001-2400.2011.04.009

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To improve the accuracy of predicting the motion vector for irregularly-shaped motion compensation partition, a novel motion vector prediction method based on the adjacent length of neighbor motion compensation partition (MVPAL) is proposed with the consideration of the spatial correlation between the motion information. Firstly, according to the conclusion that the correlation between the motion information strengthens the adjacent length, the proposed method predicts the motion vector with the motion information on the neighboring motion compensation partition with the largest adjacent length. Then, the current coding motion information is stored in the 4×4 block manner for predicting the motion vectors of motion compensation partitions in the remaining macroblocks. Experimental results demonstrate that MVPAL outperforms the existing algorithm for motion vector prediction with different resolution sequences. The average coding efficiency has been improved up to 1.47% compared with the original motion vector prediction algorithm in H.264/AVC.

Multi-stage MIMO detection algorithm with low complexity

ZHANG Qi;GE Jianhua;LI Jing

J4. 2011, 38(4):  56-60.  doi:10.3969/j.issn.1001-2400.2011.04.010

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An improved detection algorithm for the MIMO system is presented. Utilizing the group interference suppression (GIS) strategy, the received signal vector is first divided into several groups and each group consists of a pair of sub-stream, then the sub-streams within one group are detected using the low complexity parallel detection (PD) strategy, and stage-by-stage interference cancellation is performed among the groups. Theoretical analysis and simulation results show that in quasi-static flat fading channels, the proposed algorithm outperforms the traditional  Ordered Successive Interference Cancellation(OSIC) and  Maximum Likelihood Decision Feedback Equalization(ML-DFE) algorithm with a significantly lower complexity. In the 4×4 QPSK modulation MIMO system, signal-to-noise ratio improvement of 0.8～6.9dB is obtained for BER of 10^-3 with only about 52.7% and 20.1% computational complexity compared with ML-DFE and OSIC algorithm. Furthermore, additional performance benefits can be obtained by employing more antennas and high order modulation.

Joint iterative equalization and decoding for underwater acoustic coherent communication systems

ZHAO Liang;GE Jianhua

J4. 2011, 38(4):  61-65.  doi:10.3969/j.issn.1001-2400.2011.04.011

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Serially concatenated trellis coded modulation (SCTCM) technology is adopted to improve the bandwidth efficiency of the underwater acoustic channel. In order to overcome multi-path fading and eliminate inter-symbol interference (ISI), the turbo theory is applied to form the joint iterative multi-channel adaptive decision feedback equalizer (MC-ADFE) and decoder of SCTCM. In the joint iterative equalization and decoding (JIED) algorithm, the MC-ADFE and decoder of SCTCM exchange soft information in an iterative manner, which can enhance the equalizer performance using the significant decoding gain. Simulation results show that the proposed system scheme can improve the performance of the equalizer and lead to a considerable coding gain. So, the performance of the underwater acoustic communication system has been improved greatly.

Robust ground moving target detection and the velocity estimation method

WEN Jun;LIAO Guisheng;ZHU Shengqi

J4. 2011, 38(4):  66-70.  doi:10.3969/j.issn.1001-2400.2011.04.012

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For interferomatric synthetic aperture radar (InSAR) together with the ground moving target indication (GMTI) system, the problems of the terrain interferometric phase coupling and the non-stationary clutter induced by the long across-track baseline arise. To mitigate these problems, an alternative GMTI method is addressed. This method takes advantage of the coherence information to coregister two SAR images, and then removes the local flat-earth phase, compensates the terrain interferometric phase, and finally suppress the non-stationary clutter. Therefore, the GMTI function can be well performed in the existing InSAR system. Compared with conventional methods, the performance of target detection can be enhanced and the accuracy of velocity estimation can be greatly improved. Theoretical analysis and real measured data illustrate the effectiveness and practicability of the proposed GMTI method.

Clock generator with high stability for the UHF RFID chip

LIU Weifeng;ZHUANG Yiqi;ZHOU Junchao;TANG Longfei;JIN Zhao

J4. 2011, 38(4):  71-76.  doi:10.3969/j.issn.1001-2400.2011.04.013

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An improved design of the clock circuit is proposed for passive UHF radio frequency identification tag chips. Through the dynamic adjustment of the control circuits by setting capacitances and relevant calibration circuits in the traditional relaxation oscillator circuits, irrelevance is realized between the clock frequency and the working-voltage and bias current, so that the clock jitter caused by power fluctuations and deviation is suppressed so as to guarantee the stability of the clock frequency. At the same time, two kinds of resistance with positive or negative temperature coefficient and calibrating circuits are adopted to keep the clock cycle stability within a large scope of temperature variation. This circuit has been taped out with TSMC 0.18μm process. Test results show that the proposed circuits can get a more calibration scope and clock precision with power consumption of 0.86μW, which is very suitable for passive chips.

New adaptive noise suppressing method for interferometric phase images

GUO Jiao;LI Zhenfang;LIU Yanyang;BAO Zheng

J4. 2011, 38(4):  77-81+88.  doi:10.3969/j.issn.1001-2400.2011.04.014

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This paper proposes a new adaptive noise suppressing method for interferometric phase images. The key point of noise filtering for interferometric phase images is the selection of the independent and identically distributed (i.i.d.) samples. The proposed method determines filtering samples with the criterion of the minimum phase differences according to the region-growing strategy, and then computes the filtered phase in the complex domain. Due to the minimum phase difference, the proposed method selects the filtering samples that obey the i.i.d. assumption more accurately, thus improving the filtering performance. Finally, experiments carried out on simulated and real data confirm that the proposed method possesses a better filtering performance and has the ability to suppres the noise effectively while maintaining the interferogram details adequately.

SNR weighting based target detection algorithm for spatial diversity radar

ZHOU Shenghua;LIU Hongwei;LIU Baochang;YIN Kuiying

J4. 2011, 38(4):  82-88.  doi:10.3969/j.issn.1001-2400.2011.04.015

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For a spatial diversity radar, signals received by widely separated radar sites may have different signal-noise-ratios (SNRs) due to different distances between radar sites and target, which would decrease the detection performance of the conventional incoherent accumulating detector (IAD). Based on the Neyman-Pearson criterion, a signal fusion based target detection algorithm is proposed, which weights signals received by different radar sites according to channel SNRs estimated. With channel SNRs of radar sites known, this algorithm achieves the upper bound of the detection performance. Numerical experiments indicate that the proposed algorithm gives a much better detection performance than the conventional IAD, especially when channel SNRs are low.

Adaptive pulse compression for MIMO radar in cross correlation interference

LIU Yunfo;LIU Zheng;XIE Rong

J4. 2011, 38(4):  89-94.  doi:10.3969/j.issn.1001-2400.2011.04.016

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The traditional MIMO radar pulse compression algorithm has a high-level range sidelobe since the radar waveforms are generally not totally orthogonal, which causes bad detection performance. In this paper, based on maximal signal-to-inference plus noise ratio criteria, a reiteration-based adaptive pulse compression algorithm for MIMO radar is proposed. This algorithm uses the range profile information to adatively suppress the range sidelobe, interference and noise. Simulation results show that the range sidelobe can be evidently reduced and works effrctively both in moving target and multiple target cases.

Low energy consumption mapping algorithm for the network-on-chip

ZHANG Jianxian;ZHOU Duan;YANG Yintang;LAI Rui;GAO Xiang

J4. 2011, 38(4):  95-100.  doi:10.3969/j.issn.1001-2400.2011.04.017

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A mapping algorithm based on catastrophic genetic annealing is proposed, aiming at the mapping problem of low-energy consumption network-on-chip (NoC) that satisfies bandwidth constraints. Derived from a standard genetic algorithm, the proposed algorithm introduces the Boltzmann selection method and optimizes the optimum individuals upon genetic manipulation by the multi-neighborhood simulated annealing operation. Besides, some poor individuals belonging to the population in stagnation are re-initialized by catastrophic operations to jump out of local extreme values. Experimental results suggest that the presented algorithm has the advantages over the standard genetic algorithm of better optimizing performance and faster convergence. The algorithm can also save 21.7% energy on average compared to the chaos genetic algorithm in mapping results, thus effectively reducing the energy consumption of NoC system communications.

Parameter extraction method for microwave filters based on the curve fitting technique

CHEN Jianzhong;LIANG Changhong;CHEN Jia;LI Qi

J4. 2011, 38(4):  101-105+123.  doi:10.3969/j.issn.1001-2400.2011.04.018

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The traditional parmeter extraction for microwave filters usually depends on complicated optimization, or it is not suitable for lossy condition. This paper presents a new parameter extraction method for microwave filter design. The phase loading effect is analyzed and removed by using curve fitting technology, and then the unloaded quality factor of lossy microwave resonator is estimated. By making use of the least squares fitting method, admittance parameters of the filter can be extracted according to the EM simulation data, and then the coupling matrix is obtained from these parameters. The proposed approach is used to extract the parameters from EM simulation data of two kinds of microwave filters with a complicated structure. Extracted results aggree well with the simulation.

Fast analysis of electromagnetic properties of surface/surface configurations

WANG Xing;GONG Shuxi;WANG Wentao;ZHANG Yujie

J4. 2011, 38(4):  106-111.  doi:10.3969/j.issn.1001-2400.2011.04.019

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The adaptive integral method is utilized to solve electromagnetic radiation properties of conducting surface/surface configurations. For a complex structure that involves wires and surfaces, a special basis function must be introduced to deal with the rapid varying current distributions. To simplify this model, a uniform RWG basis function has been used to model the surface/surface junction by using a thin strip with no thickness instead of a wire. Then the AIM is employed to accelerate the matrix-vector multiplications and to reduce matrix storage where the full matrices are stored in a sparse form. The preconditioner is developed to decrease the number of iterations and reduce the time of solution. Finally, three numerical examples are presented to demonstrate the accuracy and efficiency of this technique.

Applied research on band notched techniques in planar printed monopole antennas

DENG Chao;XIE Yongjun;LI Lu;ZHANG Dianfu;ZOU Yongxing

J4. 2011, 38(4):  112-117.  doi:10.3969/j.issn.1001-2400.2011.04.020

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The Coplanar Waveguide (CPW) fed circular monopole antenna is improved to suppress the interference among different wireless systems. An ultra wideband (UWB) antenna with dual band notched characteristics and a tri-band antenna for WLAN/WiMAX applications are, respectively, proposed in this paper. The UWB antenna with the measured band rejection of 3.29～4GHz and 5.29～6GHz is designed by loading two pieces of polygonal slotline at the bottom of the circular patch. Its notched frequency bands cover WLAN and WiMAX systems. In the design of the tri-band antenna, the frequency band of the antenna is controlled and notched by loading the elements of slotline, resonant stub and radial slot on the antenna. This tri-band antenna renders the measured frequency bands of 2.25～2.8GHz, 3.3～3.8GHz and 5.1～5.9GHz, which cover the application bands of WLAN/WiMAX, and has good band rejected characteristics in the remaining frequency band. Both the proposed antennas are of adjustable frequency band, and are suitable for suppressing the interference among wireless systems in the complex circumstance.

Multi-spectral image reproduction with color appearance matched

LUO Xuemei;ZENG Ping;WANG Ying;ZHENG Haihong

J4. 2011, 38(4):  118-123.  doi:10.3969/j.issn.1001-2400.2011.04.021

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To solve the problem that different viewing conditions results in different color appearances between a reproduced image and its original one during multi-spectral image reproduction, a new algorithm based on color appearance mapping for multi-spectral image reproduction is presented. Firstly, through the introduction of color appearance transformation, the color appearance description of the source spectral reflectance under the source viewing condition is obtained. Then through the construction of the reverse model, high dimensionality spectra under the destinated viewing condition is estimated. Finally, to improve the spectral precision of the reproduced image, based on the source spectra, the estimated spectra are corrected by the method of metameric correction, and the reproduced spectral image is obtained, which is mapped in color appearance and approached in spectral accuracy with the original image under the variable viewing condition. Experiments show that the perceptual color difference and the spectral inaccuracy between the reproduced multi-spectral image and its original one under different viewing conditions are small, the new method preserves the spectral information on the source spectra, and achieves equal perceptual reproduction.

Analysis of antenna around electrically large NURBS platform with improved MoM-PO method

HUANG Kai;HE Zhili;ZHANG Hongwei;LIANG Changhong;SU Hang

J4. 2011, 38(4):  124-128.  doi:10.3969/j.issn.1001-2400.2011.04.022

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The conventional MoM-PO (Method of Moments-Physics Optics) method based on NURBS (None Uniform Rational B Spline) modeling is implemented by modifying the voltage matrix, the problem of iterative misconvergence may appear. To solve this problem, a method of modifying the impedance matrix is presented to avoid the potential misconvergence. Ludwig integral combining with SPM is utilized to calculate the integral of PO currents on Bezier surfaces. It overcomes the invalidity in the conventional method while keeping its efficiency. The comparison of the results obtained by this method with the ones in the literature and from pure MoM shows feasibility and accuracy of the present method.

Radial velocity estimation for the extended moving target  with distributed space-borne SAR

HE Shun;YANG Zhiwei;XU Qing;ZHANG Juan

J4. 2011, 38(4):  129-132+142.  doi:10.3969/j.issn.1001-2400.2011.04.023

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This paper describes a new radial velocity estimation method for the extended moving target of low signal-to-clutter ratio with the distributed space-borne SAR system. By velocity searching for one fitting best to the under-test signal, a fine estimation of target radial velocity can be achieved. The estimation performance would not be sacrificed in order to suppress clutter and/or interference and the high resolution radial velocity estimation can be achieved. A preliminary result against space-borne simulation data demonstrates the effectiveness of the proposed method.

Miniaturized design of the RF power divider

XING Mengjiang;YANG Yintang;LI Yuejin

J4. 2011, 38(4):  133-136.  doi:10.3969/j.issn.1001-2400.2011.04.024

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A miniaturized power divider design method by replacing the λ/4 transmission line with an equivalent circuit is proposed. By using Ferro A6 LTCC substrates with the multi-layer dielectric constant of 5.9, a bandwidth of 200MHz, the center frequency of 1.616GHz multilayer power divider is designed and measured by use of Low Temperature Co-fired Ceramic (LTCC) technology. Its performance can be comparable to the Wilkinson power divider, with its size being 3.2mm×1.6mm×0.9mm, which is less than 1/10 of the Wilkinson power divider.

Multiple data streams joint ARQ for the unicast wireless link

WANG Zhenghai;TIAN Mao;HU Shukai;WANG Xinmei

J4. 2011, 38(4):  137-142.  doi:10.3969/j.issn.1001-2400.2011.04.025

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The usage of the unicast wireless link is improved via combining the incremental redundancy versions of multiple data streams, which are requested for retransmission. Before channel decoding, retransmission data streams are respectively detected from the composite stream by the belief propagation (BP) algorithm and combined with soft information buffered at the receiver during the previous transmission phase. Moreover, by the BP algorithm, the correctly recovered data streams are cancelled from the composite stream to improve the detection performance of other erroneous streams. For multi-stream transmission over the unicast wireless link, compared with the traditional automatic repeat request (ARQ) scheme, about 10% spectrum efficiency gain can be obtained by the proposed multi-stream ARQ. Meanwhile, the complexity increase is less than 22%.

Cooperative communication scheme with 8PSK modulation constellations using LDPC codes

LI Lin;YUAN Chaowei;TIAN Xinji

J4. 2011, 38(4):  143-147+180.  doi:10.3969/j.issn.1001-2400.2011.04.026

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A new coded cooperation scheme with 8PSK modulation using LDPC codes is proposed for high spectral efficiency. Two users in the cooperative process transmit the data using 8PSK modulation over two frames. The transmitted information is stored if it is not decoded correctly by the cooperative partner over the first frame based on HARQ, and then the stored information and the next transmitted information are together decoded by the cooperative partner until the transmitted information over the first frame is decoded successfully, which improves the accuracy of decode due to adding parity information. Then the parity information of his cooperation partner is transmitted over the second frame for diversity. Analysis and simulation results show that the proposed method outperforms the no coded cooperation method and conventional coded cooperation method by benefit of 5dB and 3dB in the Raleigh block channel when the interuser channel has an SNR of 0dB and its BER is 10^-3.

Novel radar signal sorting method with low complexity

WANG Shiqiang;ZHANG Dengfu;BI Duyan;YONG Xiaoju

J4. 2011, 38(4):  148-153.  doi:10.3969/j.issn.1001-2400.2011.04.027

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The radar signal sorting method based on the traditional Support Vector Clustering(SVC) algorithm leads to a high time complexity, and the traditional validity index can not indicate the best sorting result efficiently. Aimed at the problem, a new sorting method is presented based on the Cone Cluster Labeling(CCL) method for the SVC algorithm. The CCL method relies on the theory of approximate coverings both in teature space and data space. And a new cluster validity index, Similitude Entropy (SE) index,is proposed which assesses the compactness and separation of clusters using the information entropy theory. The problem mentioned above can be resolved well with the proposed method. Experimental results show that the strategy can improve efficiency without sacrificing sorting accuracy. Meanwhile the proposed method can meet the real-time and accuracy requirements of the ELINT system to some extent and is of good practical value.

Novel localization algorithm based on evolutionary programming resampling in WSN

CHENG Wei;SHI Haoshan;LI Dong

J4. 2011, 38(4):  154-159.  doi:10.3969/j.issn.1001-2400.2011.04.028

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In order to obtain the geographic positions of random nodes in wireless sensor networks (WSN) more accurately, a new localization algorithm is proposed based on evolutionary programming resampling. After the initial position estimation is achieved based on the sampling, a small-scale evolutionary programming based position resampling is carried out, and then iterative refinement is done. In the evolution stage, two schemes, i.e., standard evolutionary programming and meta-evolutionary programming, can be employed respectively to acquire the resample positions. Simulation results show that, compared with the similar method, the proposed algorithm can reduce the mean error of location by about 20%; moreover, compared with the standard evolutionary programming method, the resamping by Meta evolutionary programming improves the localization accuracy more effectively, because of its better adaptability.

Diversity analysis of the double-antenna receiving system over double-Rayleigh fading channels

LI Zhaoxun;HU Hanying

J4. 2011, 38(4):  160-166.  doi:10.3969/j.issn.1001-2400.2011.04.029

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On the basis of the double-Rayleigh fading model, the paper investigates the diversity performance and average symbol error rate (ASER) for the double-antenna receiving system assuming maximal ratio combining (MRC) and selection combining (SC) strategies. The statistical properties of the receiving signal-to-noise ratio (SNR) are analyzed and a generalized expression on ASER is derived through MGF (moment generating function) based approach for MRC and SC schemes. Numerical calculations show that the fading effects are mitigated and that the ASER of the system is decreased by double-antenna receiving methods. They also manifest that the effective diversity gain achievable, d_e, cannot reach the full diversity order and go up slowly with the increase in SNR in double-Rayleigh fading. It also decreases with the increase in modulating orders, e. g., while the SNR is 80dB, d_e is about 2.5dB for MRC or 2.41dB for SC under BPSK modulation and it drops to 1.25dB for MRC or 1.13dB for SC under 64QAM modulation.

Moving target detection and processing method of LFMCW radar under complex background

HOU Zhi;MIAO Chen;ZHANG Jindong;WU Wen

J4. 2011, 38(4):  167-172.  doi:10.3969/j.issn.1001-2400.2011.04.030

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In order to improve the detection performance of LFMCW radar under complex background, the echo signal characteristics in the one- and two-dimensional frequency domain are analyzed and a new moving target detection method is presented. This method transforms the signal into the two-dimensional frequency domain and detects the moving target by using the 2-dimensional CFAR algorithm, which eliminates the interferences from complex background. After detection, by utilizing the information in the 2-dimensional frequency domain, the target range, velocity and azimuth angle are acquired and trajectory is measured. Simulation and experimental results demonstrate the effectiveness of this method.

Improved cancelable fingerprint fuzzy vault system

ZHANG Ronglin;LIU Eryun;ZHAO Heng;PANG Liaojun

J4. 2011, 38(4):  173-180.  doi:10.3969/j.issn.1001-2400.2011.04.031

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Fuzzy vault has been widely applied in biometric encryption domain for key binding, suitable for set feature representation, such as minutiae set of fingerprint image. However, with the real minutia points contained in vault, fuzzy vault is suffered from cross matching problem, which makes attackers easily obtain real minutia information from multiple vault templates and threatens user privacy and secret key security. In this paper, an improved cancelable fuzzy vault scheme is proposed, in which an one-way function based on password is constructed to transform original minutia information and then the transformed minutiae are fed to fuzzy vault system. The attackers can not obtain the original minutia features even though multiple vaults are at hand, and the users can reissue a new vault template by changing password. Experimental results on FVC2002 DB2 show that the proposed method can effectively reduce the hidden troubles and increase security of system.