Table of Content

31 January 2014, Volume 32 Issue 1

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Communication Engineering

Resource Allocation for Capacity-Maximization in SC-FDMA Relay Systems

ZHU Yu, ZHANG Meng-ying

2014, 32(1):  1-6.  doi:10.3969/j.issn.0255-8297.2014.01.001

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 Resource allocation algorithms are proposed to maximize the capacity of single carrier frequency division multiple access (SC-FDMA) relay systems. Taking into account the subchannel adjacency restriction of SC-FDMA, an optimal algorithm is presented to reformulate this problem as a set partitioning problem.
By using the relevant methods in operations research, the optimal solution can be obtained. A suboptimal algorithm based on the greedy heuristic thinking is also proposed to reduce computational complexity of the optimal resource allocation. Simulation results show that, in amplify-and-forward and decode-and-forward relay-assisted SC-FDMA systems, spectral efficiency of the optimal algorithm is much higher than that of the random algorithm. The greedy algorithm with much lower complexity performs quite close to the optimal algorithm.

Coding-Aware Routing by Fully Considering Coding Opportunity

ZHAO Yun-long1, WANG Bo-shi1, ZHANG Kai1, DONG Zhao1, ZHANG Lei2

2014, 32(1):  7-12.  doi:10.3969/j.issn.0255-8297.2014.01.002

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A key in applying networking coding techniques in wireless networks is to explore more coding opportunities. A maximal coding opportunity discovery scheme is proposed, and by combining it with existing coding-aware routing protocols, a coding-aware routing protocol termed extended coding aware routing (Ex-CAR) is presented. The protocol takes maximal coding opportunity into consideration and selects the coding node number as a metric to determine the best forwarding node along the optimal route. Simulation experiments in NS-2 show that the proposed algorithm is effective, and ExCAR can enhance the network throughput and improve packet delivery rate.

QoS Guarantee for Mixed-Service in OFDM Relay System

DAI Cui-qin, WANG Liang, WANG Hai-bao

2014, 32(1):  13-18.  doi:10.3969/j.issn.0255-8297.2014.01.003

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 To ensure QoS requirements for mixed-service in an orthogonal frequency division multiplexing relay system, we propose a relative largest queue aware first/relative proportional fair (R-LQAF/RPF) scheduling algorithm. By setting a relative variation function, we use an RPF scheduling algorithm to enhance the
realtime user throughput to meet the actual user rate requirements. We also use an R-LQAF scheduling algorithm to improve the scheduling performance, decrease the packet loss rate, and ensure QoS requirements for non-realtime user according to the relationship of the user queue length and the system queue length.Simulation results show that, compared with the existing proportional fair and the largest weighted delay first algorithm, the R-LQAF/RPF algorithm can flexibly choose different scheduling strategies for different businesses, effectively improve user performances in terms of throughput, packet loss rate, and satisfaction of demanded rate, and guarantee QoS requirements of mixed businesses.

Quantum-Inspired Shuffled Frog Leaping Algorithm for Spectrum Allocation in Cognitive Radio

GAO Hong-yuan1, CAO Jin-long2

2014, 32(1):  19-26.  doi:10.3969/j.issn.0255-8297.2014.01.004

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To solve a discrete optimization problem, a quantum-inspired shuffled frog leaping (QSFL) algorithm based on shuffled frog leaping algorithm and quantum information theory is proposed. The QSFL algorithm uses quantum movement equations to find the optimal location by the co-evolution of quantum frog colony. Good performance of the QSFL algorithm is shown by some classical benchmark functions. At the same time, we design an assignment method for cognitive radio spectrum allocation without interference based on it. Simulations are conducted to compare this method with genetic algorithm (GA), quantum genetic algorithm (QGA), particle swarm optimization (PSO), shuffled frog leaping algorithm (SFLA) and color-sensitive graph coloring (CSGC) using different network utility functions. Simulation results indicate that the proposed method can find the near-optimal solution. It outperforms the color-sensitive graph coloring and the previous intelligent spectrum allocation methods.

Multi-user Two-Way Relay Power Control for CDMA System

ZHANG Er-wei, QIU Ling

2014, 32(1):  27-31.  doi:10.3969/j.issn.0255-8297.2014.01.005

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For multi-user two-way relay in CDMA systems, bit error rate (BER) of the first jump is approximated,an efficient function of power control obtained, and an iterative algorithm for power control provided.Exsitence and uniqueness of Nash equilibrium is proved theoretically. Simulation results show reliability, fast
convergence, and low power of convergence of the proposed approximation. Compared to traditonal algotithms,the proposed method can reduce the average transmit power with large number of users in the system.

Optimized Interleaver for Protograph LDPC Coded BICM with High Spectral Efficiency

DOU Jin-fang1, HE Shan-bao2, JIANG Ming3

2014, 32(1):  32-38.  doi:10.3969/j.issn.0255-8297.2014.01.006

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As a crucial part in bit-interleavered coded modulation (BICM), protograph low-density paritycheck(P-LDPC) codes and interleavers can greatly improve the performance of a BICM system. In this paper, we use a modified EXIT analysis method to analyze thresholds for a P-LDPC coded BICM system
with high-order QAM in different variable degree matched mapping (VDMM) schemes. A general criterion for optimization of VDMM interleavers is proposed. Results of numerical analysis and simulation show correctness of the optimization criterion.

Polarization Dependent Loss in Coherent Optical Systems

HAO Yao-hong1, LENG Dan1, FANG Tao2

2014, 32(1):  39-43.  doi:10.3969/j.issn.0255-8297.2014.01.007

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Coherent optical OFDM system (CO-OFDM) is a promising technology in high speed long-haul optical transmission. Polarization dependent loss (PDL) and first-order polarization mode dispersion (PMD) influence system performance seriously in high speed transmission. The mathematical model of transmission is analyzed, and a signal equalization scheme is proposed for CO-OFDM systems. Numerical simulation is done to validate the method and the estimation algorithm. Analysis and simulation results show that the polarization effect may cause amplitude noise and phase noise, which can be eliminated with signal equalization. At a length of 720 km, the Q value is improved by 0.8 dB for = 1 compared with = 0.5. Meanwhile, the first-order PMD may reduce the PDL effect by rotation of SOP (state of polarization).

Signal and Information Processing


Effects of Forgetting Factor on RLS Dictionary Learning  

YU Fu-ping1,2, FENG You-qian1, LEI Teng1, LI Zhe1

2014, 32(1):  44-50.  doi:10.3969/j.issn.0255-8297.2014.01.008

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Dictionary learning is a hot topic in signal sparse decomposition. The choice of the initial dictionary affects the result of dictionary learning. In order to reduce the effects, a forgetting factor is introduced into the recursive least squares (RLS) dictionary learning. The dictionary learning effects of three dictionary
learning methods, method of optimal directions (MOD), K singular value decomposition (KSVD), and RLS are compared. Influences of different fixed forgetting factors on the final learned dictionary are analyzed,and the results of dictionary learning with different forgetting factors studied. Simulation shows that the RLS dictionary learning reduces the influence of the initial dictionary, and gives better effects. Results of the dictionary learning are influenced by the choice of the forgetting factor.

Design of Directional Modulation Signal Based on Multi-objective
Genetic Algorithm for Physical Layer Secure Communication

HONG Tao1, SONG Mao-zhong2, LIU Yu2

2014, 32(1):  51-56.  doi:10.3969/j.issn.0255-8297.2014.01.009

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A directional modulation signal based on multi-objective genetic algorithm is proposed. According to the relationship between Euclidean distance of constellation points and bit error rate performance, the phase shift values are generated by means of optimizing multi-objective genetic algorithm to synthesize a directional modulation signal. This signal transmits different signal constellation at different directions. In the desired direction, the signal’s constellation is the same as the traditional baseband modulation signal while the constellation is scrambled in other directions. Compared with the traditional directional modulation signal, the proposed directional modulation signal has a narrower beam-width. Simulation results show that the technique
offer a better physical layer secure transmission signal for wireless communication.

Multi-dimensional Angle Estimation in Bistatic MIMO Radar for L-Shaped Array with Propagator Method

SUN Zhong-wei, ZHANG Xiao-fei, WU Hai-lang, LI Jian-feng

2014, 32(1):  57-64.  doi:10.3969/j.issn.0255-8297.2014.01.010

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 Computation complexity of spatial spectrum estimation algorithm is high. To solve this problem,a PM algorithm is introduced for estimation of 2D direction of departure (DOD) and 2D direction of arrival (DOA) for bistatic MIMO radar. A propagator is estimated using the cross correlation matrix. By rotationinvariance
of the propagator, one can estimate the direction of the matrix, and further estimate DOD and DOA. The algorithm has low computation complexity, and can achieve multi-dimensional automatic pairing. With similar angles, good performance is still maintained. In the case of high SNR, performance of the proposed algorithm is close to that of the ESPRIT. Mean square error of angle estimation is derived. Simulation results verify the usefulness of the algorithm.

Image Self-Embedding Based on EZW Coding and Fountain Codes

LIAO Chun, QIAN Zhen-xing, NI Jing, WANG Shuo-zhong

2014, 32(1):  65-73.  doi:10.3969/j.issn.0255-8297.2014.01.011

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We first utilize EZW to encode the wavelet coefficients of the image, and then the fountain encoding to generate the reference data. By extracting forensic data and reference data which is self-embedded into the image, tampered area is detected and reference data is also reconstructed. Comparing to block-based DCT,we overcome the blocking artifact of the recovered image. Besides this, we propose a method which makes the data embedding and image quality dynamic by adjusting the parameters. A balance between the recovered area and recovered quality is also achievable.

Frontal Face Synthesis Based on Improved Binocular Stereo Vision

WANG Jing1,2, SU Guang-da1

2014, 32(1):  74-78.  doi:10.3969/j.issn.0255-8297.2014.01.012

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To improve the face recognition performance under different poses, we propose an improved frontal face synthesis method based on binocular stereo vision, which can effectively and quickly synthesize a frontal face. A modified matching algorithm is designed to deal with smoothness of faces. Then 3-D coordinates are generated according to the disparity image, and the pose angle of the face calculated according to the location of eyes. A frontal face is generated according to the pose angle using the method of binocular stereo vision.Experimental results show that the method is precise, practical, and fast.

Generation of Epipolar Images from ZY-3 Satellite Fused Data

JIA Yong-hong1,2, ZHU Meng-hua1, DIAO Yong-zhou1, GUAN Yu-juan3

2014, 32(1):  79-84.  doi:10.3969/j.issn.0255-8297.2014.01.013

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 A high-resolution color epipolar image generation method is proposed based on image fusion. A pair of panchromatic stereo images is fused with registered multispectral images. Approximate epipolar images based on projection reference plane (PRP) are then generated according to the practical epipolarity model for linear pushbroom satellite stereo-imagery. Thus, generation of high-resolution color epipolar images is realized.Experimental results of the ZY-3 data show that the proposed method has the same measurement performance in revealing true terrain features, and can provide more information and better visual interpretation.

Design and Implementation of CUDA Algorithms Based on Nonlinear Image Diffusion LB model

ZHOU Ming, YAN Zhuang-zhi, HUANG Bin

2014, 32(1):  85-92.  doi:10.3969/j.issn.0255-8297.2014.01.014

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 To improve the performance of Lattice Boltzmann (LB) method in image denoising, this paper proposes three compute unified device architecture (CUDA) algorithms to realize streaming processes of LB in nonlinear image diffusion, which are based on texture memory, shared memory, and global memory, respectively.To test effectiveness and efficiency of the GUDA algorithms, experiments were carried out with natural and composite images. The results show that GPU acceleration is 90 times faster than CPU acceleration, and the factor is proportional to the number of GPU stream processors.

Vehicle Identification and Counting Based on Sparse Over-Completeness

LU Peng1, LOU Ya-fei1, LIU Feng-zhe2, LI Yu-song1, HUANG Shi-lei1, TANG Yu-he1

2014, 32(1):  93-98.  doi:10.3969/j.issn.0255-8297.2014.01.015

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To detect and count high-speed vehicles accurately and robustly, a sparse over-complete model is established to simulate the visual mechanism. The model uses image units as processing objects. It expresses the internal structure and essential attributes of the target image with a small amount of non-zero response sparse coefficients, and identifies different types of vehicles in different environments. Online counting of vehicles is achieved by setting dynamic lanes based on virtual detection lines. Accuracy of the vehicle counting reaches 98.89% under a variety of environmental conditions. The results show that the proposed algorithm can effectively suppress interference caused by external factors such as wind, light changes and camera shakes. It
has higher robustness and accuracy than traditional algorithms.  

Control and System

Observer Design for a Class of Linear Switched Systems

YANG Yin, SUN Wen-an, PEI Bing-nan

2014, 32(1):  99-104.  doi:10.3969/j.issn.0255-8297.2014.01.016

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This paper focuses on the problem of observer design for a class of linear switched systems. By constructing appropriate Lyapunov functions and using matrix inequalities, conditions of the exponential convergence of the estimated state observer are obtained. Furthermore, by using state jump at certain time when the change of value of the switched law occurs and specifying the value of the state jump, the system performance is improved. It is shown that the convergence rate of the estimation error can be reduced significantly. Simulation results are given to show validity of the state observer.

Inland Waterway Ship Tracking Using a TLD Framework

TENG Fei, LIU Qing, GUO Jian-ming, ZHOU Ya-qi

2014, 32(1):  105-110.  doi:10.3969/j.issn.0255-8297.2014.01.017

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Closed circuit television (CCTV) systems are widely used in the video surveillance of inland waterway. A framework of tracking-learning-detection (TLD) is presented and further enhanced to address the problem of ship identification and tracking in the inland waterway CCTV system. A constraint condition for the
eigenvalues is proposed to examine the short-term tracking results so that complexity in calculating normalized cross correlation is avoided. Meanwhile, tracking results for corners in the image are accurately reserved, making the short-term tracking results reliable. Ships can be located accurately by applying cascaded detectors. A template matching method is proposed to ensure accuracy of the algorithm. Extensive experimental results show that the proposed algorithm outperforms the original TLD framework in terms of efficiency, accuracy and robustness.