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• • 2016, Vol. 39 No. 6 Published date:28 December 2016 Last issue Next issue

  Papers

  • Channel Capacity on Additive White Gaussian Noise Channel under Overlapped Multiplexing Principle
  • LI Dao-ben
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 1-10. DOI:10.13190/j.jbupt.2016.06.001
  • Abstract ( 359 )     HTML     　　
  • In order to offer a new theoretical foundation for constructing huge capacity communication system without increasing system bandwidth, it has been verified that under additive white Gaussian noise environment, if the transfer function H(f) of the channel has a limited bandwidth B (single side), the duration T of the impulse response function h(t) goes to infinite, the space between independent samples are 1/2B and 0 respectively in time and frequency domain. It is not sufficient to only employ independent signaling samples separated by 1/2B Sec in time domain like Shannon, it should be also to employ independent signaling samples separated by B/K Hz in frequency domain. In this way, the channel capacity is proportional to K. Since the space between independent samples is 0 in frequency domain, K has no limited. The Shannon capacity is only a special case of ignoring the independent signaling samples in frequency domain (K=1). Similarly if the impose response function h(t) of the channel has a limited time duration T, the bandwidth B of the transfer function H(f) goes to infinite, the space between independent samples are 0 and 1/T respectively in time and frequency domain. It is not sufficient to only employ independent signaling samples separated by 1/T Hz in frequency domain like orthogonal frequency division multiplexing, it should be also to employ independent signaling samples separated by T/K Sec in time domain. Similarly, the channel capacity is proportional to K. Since the space between independent samples is 0 in time domain, K has no limited. And the essential of overlapped multiplexing principle is to construct independent parallel Gaussian channels.
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  • Overlapping Cell Segmentation Based on Level Set and Concave Area Detection
  • YANG Hui-hua, ZHAO Ling-ling, PAN Xi-peng, LIU Zhen-bing
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 11-16. DOI:10.13190/j.jbupt.2016.06.002
  • Abstract ( 623 )     HTML     　　
  • Overlapping cell images with inhomogeneity intensity, low contrast and edge blurring are difficult to be segmented. The author proposes a new cell segmentation algorithm combining level set method and concave area detection. First, the level set method can easily handle topology changes of the evolving contour. And it can be employed to obtain the cell profile, combined with the regional information and edge information. This step keeps the geometric characteristics of the cell profile effectively. Second, the concave area of overlapping contour location based on the concave and convex of polygons was searched for. Finally, the splitting line of overlapping cells at the location of concave area was determined. Experiments on dozens of different overlapping cell images segmentation show that the algorithm is robust, effective and easy to implement. The average accuracy of cell segmentation reaches to 83.01%, which is superior to the results of the watershed and k-means clustering methods.
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  • A Wireless Health Monitoring System Based on iOS
  • ZHANG Jin-ling, GAO Zhi-xin
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 17-21. DOI:10.13190/j.jbupt.2016.06.003
  • Abstract ( 230 )     HTML     　　
  • To solve the problem of single function on the community health care and domestic medical equipment, and improve both the reliability and the portability of the health care equipment of electrocardiogram and blood oxygen parameters, a mobile wireless healthy monitoring system was proposed based on the Bluetooth low energy protocol and utilization of the acquisition equipment of physiological parameters depending on existing researches. A system was designed by combining the thought of the mobile health, which includes the hardware of Bluetooth module, the protocol stack of Bluetooth low energy, mobile phone application, and file server etc. It realizes the real time monitoring, displaying and storing of the electrocardiogram and blood oxygen parameters. Experiments show that the system has good performances on transmission and portability owing to small size, and it can meet the requirements of daily health care.
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  • An Improved Min-Sum Decoding Algorithm for Polar Codes
  • HONG Yin-fang, LI Hui, WANG Xin-mei
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 22-26. DOI:10.13190/j.jbupt.2016.06.004
  • Abstract ( 532 )     HTML     　　
  • In order to enhance the performance of the min-sum decoding algorithm for polar codes, an improved min-sum decoding algorithm was proposed. The improved method corrects the node update formulas of the min-sum decoding algorithm which replaces the function lncosh(x) in the belief propagation (BP) decoding algorithm with the piecewise linear approximation functions. Compared with the min-sum decoding algorithm, the modified decoding algorithm has better performance in case of increasing a little complexity. Compared with the BP decoding algorithm, the algorithm greatly reduces the computational complexity in case of almost no performance loss, and simplifies hardware implementation. The modified algorithm is based on the min-sum and the BP algorithms, and it is a compromise between the complexity and performance. Simulations show that the performance of the improved min-sum decoding algorithm is almost the same as the BP decoding algorithm, and better than the min-sum decoding algorithm.
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  • Copy-Move Forgery Detection Algorithm Based on HSV and CLAHE
  • ZHANG Wei-wei, YANG Zheng-hong, NIU Shao-zhang
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 27-32. DOI:10.13190/j.jbupt.2016.06.005
  • Abstract ( 341 )     HTML     　　
  • The existing local feature point-based methods such as scale-invariant feature transform (SIFT) and speeded up robust features (SURF) cannot be accurately extracted as feature points especially in terms of forgeries involving small areas and smooth regions. A two-stage forgery detection method which is based on the hue, saturation and value (HSV) color space and contrast limited adaptive histogram equalization (CLAHE) was proposed. In the first stage, the tested image is converted from red, green and blue (RGB) color space to HSV and then SURF features were extracted in this space. In the second stage, in order to resist tampering in smooth regions, CLAHE algorithm was used as a preprocessing stage to the SURF algorithm. After feature extraction, generalized 2 nearest neighbor (g2NN) matching skills were used in the matching step. At last, the random sample consensus (RANSAC) was used to remove the false matches. The location of the tampered area is achieved by morphological operations. Experiments show that the proposed algorithm not only can resist copy-move forgeries in small areas and flat regions with non-significant visual features but also robust to post-processing operations such as rotation, scaling and so on.
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  • Real-Time Static Polarimetric Image Dehazing Technique Based on Atmospheric Scattering Correction
  • XIA Pu, LIU Xue-bin
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 33-36,71. DOI:10.13190/j.jbupt.2016.06.006
  • Abstract ( 420 )     HTML     　　
  • In order to realize real-time static image recovery under hazy weather, a new theory of polarimetric dehazing was presented based on study of the atmospheric scattering model, analyzation on the effects of aerosols and the method of atmospheric scattering correction. The polarimetric information is obtained statically from the original images by Stokes equation and the Muller matrix. The sky region is extracted in real time based on the polarimetric measurement of the hole image. The influence of the range of polarization orientation angle and the threshold of air light intensity are analyzed based on the extraction result. The real time static polarimetric image dehazing method can be realized with fixed linear polarimetric images. No manual operation or subjective evaluation is needed which greatly simplifies the dehazing process. The accuracy of image recovery is increased by solving the problem of the estimation of the global parameters. The real time static polarimetric dehazing method provides a new theoretical and technical way for high-resolution, high stability and real-time image recovery under hazy weather.
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  • MBER Optimization Algorithm for Communications with Wide Band Power Amplifiers
  • LOU Jian-ming, ZHU Ren-xiang, ZHENG You, ZHONG Qiu-bo
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 37-41. DOI:10.13190/j.jbupt.2016.06.007
  • Abstract ( 356 )     HTML     　　
  • A joint compensation by digital pre-distortion and nonlinear equalizers was proposed for nonlinear distortion of wide band power amplifiers in communications. The nonlinear equalizers are based on minimum bit error rate (MBER) algorithm. Out-band interference caused by nonlinear distortion is suppressed by digital pre-distorters, and in-band distortion is reduced by nonlinear equalizers. Simulations show that the performance of nonlinear equalizers based on MBER is superior to that based on minimum mean square error algorithm. Through joint compensation of pre-distortion and equalization, the digital distorters can be simplified and the performance of bit error rate can be improved.
  • References | Supplementary Material | Related Articles

  • Personalized Cloud-media Services Selection by QoS Prediction
  • TANG Rui-chun, FANG Li-hua, PANG Min, XU Xiao-wei, DING Xiang-qian
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 42-46. DOI:10.13190/j.jbupt.2016.06.008
  • Abstract ( 312 )     HTML     　　
  • In order to improve the quality of service (QoS) and the user satisfaction of cloud-media services selection, a personalized cloud-media services selection based on QoS prediction was proposed. Firstly, a credibility model is established and introduced to the calculation of user similarity to optimize the neighbor users, then the QoS value of unused services can be predicted by and the collaborative filtering, services having higher services quality are selected as candidates. Secondly, the user preferred cloud-media services is provided on the basis of technique for order preference by similarity to an ideal solution to improve the user satisfaction. Simulation results show its efficiency.
  • References | Supplementary Material | Related Articles

  • LEACH Coverage Preserving Protocol Based on Dead Nodes and Radius Scheduling
  • DONG Ying, NI Jia-wei, WU Hao, CUI Meng-yao, WANG Yu-hou
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 47-52. DOI:10.13190/j.jbupt.2016.06.009
  • Abstract ( 275 )     HTML     　　
  • A low energy adaptive clustering hierarchy (LEACH) coverage preserving protocol based on dead nodes and radius scheduling (LEACH_DNA) was proposed. The selection of the cluster head adopts the optimized random selection mechanism in the algorithm. The cluster head nodes are divided by Voronoi diagram. And there are several clusters divided by the coverage radiuses of the cluster head nodes and the coverage radiuses of the clusters inter nodes. When the radiuses of cluster nodes increases, the radiuses of cluster nodes and considered the number of dead nodes in the network reduces. The function of the executive thereafter chooses a certain number of clusters nodes and renews the LEACH clustering. Simulation shows that the LEACH_DNA algorithm for network coverage has maintained at 1 700 round, the function of the network data transmission capacity is improved, and the network life time is extended.
  • References | Supplementary Material | Related Articles

  • Channel Characteristics of Dual-Polarized MIMO System for Indoor Scenario
  • LI Yi-wei, TANG Xuan, LIN Bang-jiang, ZHANG Shi-hao
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 53-56. DOI:10.13190/j.jbupt.2016.06.010
  • Abstract ( 487 )     HTML     　　
  • For research on channel characteristics of dual-polarized multiple input multiple output (MIMO) system, the channel measurements were carried out using Elektrobit multi-dimensional radio channel sounder for line-of-sight and non-line-of-sight routes in indoor office. The channel characteristics were investigated by the power delay profile, root mean square delay spread, channel capacities and cross polarization discrimination. It can be found that the parameters have different propagation behaviors in horizontal polarized, vertical polarized and dual-polarized case. The simulation results show that dual-polarized MIMO system will increase the multipath components, and the channel capacity can be significantly improved compared to single-polarized. The results in this paper are critical for indoor MIMO system design as well as for link and system level simulations.
  • References | Supplementary Material | Related Articles

  • Low-Complexity MMSE Detection Methods for Massive MIMO Networks
  • WANG Bin, CHANG Yong-yu, QUAN Wei, ZHANG Jian
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 57-61. DOI:10.13190/j.jbupt.2016.06.011
  • Abstract ( 472 )     HTML     　　
  • An efficient low-complexity minimum mean-squared-error (MMSE) receiver structure for massive multiple-input multiple-output (massive MIMO) networks is proposed. It is based on the steepest descent and least mean-square algorithms which can be devoid of the matrix inverse operation.The two algorithms are proved to be convergent when applied in the MMSE detection.Factors that affect the rate of convergence are also analyzed.Analysis and simulation shows that the proposed receiver architecture enjoys a low complexity property and can provide virtually the same performance as the conventional MMSE receiver.
  • References | Supplementary Material | Related Articles

  • High Performance Synchronization Algorithm in U-OFDM Based Visible Light Communications
  • HUO Jia-hao, ZHOU Xian, HUANGFU Wei, TU Jia-jing, DU Zhi-yuan
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 62-66. DOI:10.13190/j.jbupt.2016.06.012
  • Abstract ( 435 )     HTML     　　
  • Visible light communications is a new type of wireless communications technology. Combined with lighting and communications, it has characteristics of energy efficiency, rich frequency domain resources with no electromagnetic radiation, and so forth. In order to improve the transmission efficiency of optical communication system and resist multipath effect in free space transmission, unipolar orthogonal frequency division multiplexing technique (U-OFDM) was studied in detail. Due to the unipolar characteristics of U-OFDM signal, there is no specific synchronization algorithm. Therefore, a new synchronization algorithm-negative mirror image was proposed. This algorithm can achieve desired effect of synchronization in low signal to noise ratio.
  • References | Supplementary Material | Related Articles

  • Source Coding Based Recoverable Privacy-Preserving Data Aggregation Scheme
  • XU Jian, YANG Geng, CHEN Zheng-yu, WANG Hai-yong, WANG Qian-qian
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 67-71. DOI:10.13190/j.jbupt.2016.06.013
  • Abstract ( 444 )     HTML     　　
  • Based on source coding technology, recoverable privacy-preserving data aggregation scheme for wireless sensor networks was proposed. The sensor data is hidden and compressed by source coding technology according to the correlation between them. Secondly, the coded data is converted and concatenated so that the base station can recover it. Meanwhile, the base station verified the integrity of data in accordance with aggregate signature. Experiment results demonstrate that the proposed scheme can realize the recovery of original data on the basis of protecting data privacy as well as decreasing redundant transmitted data.
  • References | Supplementary Material | Related Articles

  • STP-Based Approach to Modeling and Reachability Analysis of a Class of Petri Net Systems
  • HAN Xiao-guang, CHEN Zeng-qiang, ZHANG Kui-ze, LIU Zhong-xin, ZHANG Qing
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 72-76. DOI:10.13190/j.jbupt.2016.06.014
  • Abstract ( 255 )     HTML     　　
  • Modeling and reachability of a class of Petri net systems (PNSs) by using the semi-tensor product of matrices (STP) was investigated. First, the dynamics of PNSs, by resorting to STP, are converted into a discrete-time bilinear equation. Second, the transition-state adjacency matrix of the PNSs is defined, several necessary and sufficient conditions are obtained for the reachability of the PNSs by means of this bilinear equation and transition-state adjacency matrix. A new algorithm is also designed to find all of the firing sequences of any two reachable states. Finally, an example is presented to illustrate the theoretical results.
  • References | Supplementary Material | Related Articles

  Reports

  • Linear Signal Detection Based on Simplified Matrix Inversion in Massive MIMO Systems
  • SHEN Bin, HUA Quan, WANG Qian, ZHAO Shu-feng
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 77-81. DOI:10.13190/j.jbupt.2016.06.015
  • Abstract ( 298 )     HTML     　　
  • For the uplinkchain of massive multiple-input multiple output (MIMO) system, conventionalminimum mean square error (MMSE) linear detection algorithm achieves nearlyoptimal performance when the number of antennas at the base station (BS) ismuch larger than the number of single-antenna users. However, the MMSEdetection algorithm involves complicated matrix inversion, thus making itdifficult to be implemented rapidly and effectively. In order to make atradeoff between detection accuracy and computational complexity, this paper comparesand analyzes polynomial expansion based matrix inversion approximation method andlinear equation iterative solving based equivalent approach of matrix inversion.Finally, we further propose to apply them in soft decision to make full use ofthe soft information of channel coding and decoding. In this way, it is feasibleto reduce complexity while achieving near optimal detection performance.
  • References | Supplementary Material | Related Articles

  • An Energy-Efficient Multi-Path Data Distribution Mechanism Based on RPL
  • ZHU Li-cai, WANG Ru-chuan, YANG Hao, SHA Chao
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 82-87. DOI:10.13190/j.jbupt.2016.06.016
  • Abstract ( 356 )     HTML     　　
  • An energy-efficient multi-path routing protocol for low-power and lossy networks (RPL) distribution mechanism, energy-efficient routing protocol for low-power and lossy networks (EM-RPL), was proposed to solve the problem on imbalance of power consumption in RPL. Firstly, a model of node energy consumption was established, which is more in line with the actual node energy consumption. Secondly, an energy dispersion degree measurement criterion was presented. Based on this measure, a fast algorithm was proposed to obtain the optimal distribution of the data. Simulation results show that the improved RPL algorithm can balance the energy consumption of nodes, improve the reliability of routing, and prolong the lifetime of the network.
  • References | Supplementary Material | Related Articles

  • Robust Visual Tracking Based on Mixed Features
  • REN Nan, DU Jun-ping, ZHU Su-guo, LI Ling-hui, JangMyung Lee
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 88-92,98. DOI:10.13190/j.jbupt.2016.06.017
  • Abstract ( 378 )     HTML     　　
  • In order to deal with scale variation, illumination changes and deformation of the target in tracking tasks, a visual tracking algorithm based on mixed features, called SoH-DLT, was proposed, considering both the contour features and detail features. Orientation histogram is introduced to describe the contour features of candidate samples in the process of particle filter, ensuring that the particle which is the most similar with the target can still get a high degree of confidence and can be output as the result of tracking in the case of scale, illumination changes and deformation. Speed-up robust features (SURF) feature and high-level features from deep learning are integrated to calculate the weights of particles, improving the tracking accuracy in complex scenes and enhancing the robustness of SoH-DLT to scale variation. Experiments show that SoH-DLT algorithm has better tracking performance than the contrast algorithms in both quantitative and qualitative evaluation.
  • References | Supplementary Material | Related Articles

  • Design, Implementation and Evaluation of ASIC-Based OpenFlow Switch
  • FEI Ning, CHEN Chun-ling, MAO Yan-qin
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 93-98. DOI:10.13190/j.jbupt.2016.06.018
  • Abstract ( 302 )     HTML     　　
  • OpenFlow is a de-facto standard programming interface between controllers and switches. How to enable the existing switches to support OpenFlow without losing their original forwarding capability is a challenge in the migration from traditional network to software defined network (SDN). Take Broadcom Trident series application specific integrated circuit (ASIC) switch as an example, an algorithm to map OpenFlow forwarding table entries into ASIC's ternary content addressable memory (TCAM) as well as traditional L2/L3 tables to augment the OpenFlow table's capability, was proposed. The feasibility and scalability of our solution was demonstrated with design, implementation and evaluation in physical switch.
  • References | Supplementary Material | Related Articles

  • Trust Evaluation of Web User Behavior with Weight Optimal Balance
  • TIAN Li-qin, LI Jun-jian, WU Ze-nan
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 99-103,130. DOI:10.13190/j.jbupt.2016.06.019
  • Abstract ( 365 )     HTML     　　
  • Aiming at the safety problem of the web user information, proposed a subjective and objective method of user behavior trust evaluation model. Using the entropy-weight-method to calculate the objective weight and analytic-hierarchy-process to determine the subjective weight, then combining the previous two results to further calculate the integrated weights with optimal balance, also introduced long-term quantitative evaluation mechanism based on the Sliding Window. Finally, through the dimensionless treatment of various type evidences and get the final user-behavior trust evaluation value. The theoretical analysis and practical application show that the model can meet the subjective and objective relative balance optimization conditions, and can get more accurate user behavior trust evaluation value for each-time and long-time interaction. It lays the solid foundation of theory and practice for high reliable analysis of user behavior in key network application such as e-commerce and online bank.
  • References | Supplementary Material | Related Articles

  • The Application of Kalman Filtering-BP Neural Network in Autonomous Positioning of End-Effector
  • HU Yan-zhu, LI Lei-yuan
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 110-115. DOI:10.13190/j.jbupt.2016.06.021
  • Abstract ( 369 )     HTML     　　
  • The real-time calculation of positioning error, error correction and state analysis is a difficult challenge in the process of end-effector autonomous positioning. In order to solve this problem, the Kalman filtering based on three-frame subtraction is proposed to capture the moving end-effector. Back propagation (BP) neural network is adopted to recognize the target. And 3D information extraction based point cloud library (PCL) is described to calculate the space coordinates of the end-effector and the target. The scattered points are processed by gridding and interpolation. Experiments demonstrate that the end-effector positioning can be corrected in a short time. The prediction accuracy of position reaches 99% and the recognition rate of 99% is achieved for target object. Furthermore, the gradual convergence of end-effector center (EEC) to the target center (TC) shows that the autonomous positioning is successful. The algorithm effectiveness is also validated by 3D fitting, but the camera calibration is not required. The system efficiency is improved.
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  • The Impact Factors of Mobile Node Connectivity for Opportunistic Sensor Networks
  • LIU Lin-lan, LIU Qun, GUO Kai, HAN Yang
  • Journal of Beijing University of Posts and Telecommunications. 2016, 39(6): 116-120. DOI:10.13190/j.jbupt.2016.06.022
  • Abstract ( 216 )     HTML     　　
  • According to the features of network communication through node movement in opportunistic sensor networks, a mobile node connectivity model was proposed by studying their impact factors, which dipicts connectivity of mobile nodes.In region-divided opportunistic sensor networks, the time series characteristic factors of mobile nodes were analyzed, and connectivity factors, related with them, were obtained.Monadic regression was employed to get the relationship between impact factors and delay. Based on the regression combination analysis, the mobile node connectivity model was constructed.Simulations show that the model can reflect the mobile node connectivity.
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