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    25 June 2014, Volume 35 Issue 6
    Invulnerability of small-world network against cascading failure based on nonlinear load-capacity model
    2014, 35(6):  1-7. 
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    To investigate the invulnerability of small-world networks against cascading failure, an improved nonlinear load-capacity model was introduced. Under the rule of local weighted load redistribution, the influence of weight coefficient, capacity parameters and density of the network on invulnerability of small-world networks against cascading failure was studied by numerical simulation. Then, qualitative analysis of invulnerability of small-world networks under the restrictions of cost and performance was presented. The results demonstrate that, invulnerability of small-world networks weakens with the increasing of the weight coefficient. In addition, the spreading of cascading failure of small-world networks with different density slows down when the weight coefficient is smaller, and that of the sensitiveness to network density is different. Moreover, there exists an optimal combination of capacity parameters which ensures that small-world networks reach the strongest invulnerability level. Research findings will provide useful guidance and reference in the optimization design of invulnerability for real complex networks.
    Academic paper
    Invulnerability of small-world network against cascading failure based on nonlinear load-capacity model
    Xiao-ping WU,Jia-sheng WANG,Yan-lin QIN,Qing YE
    2014, 35(6):  1-7.  doi:10.3969/j.issn.1000-436x.2014.06.001
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    To investigate the invulnerability of small-world networks against cascading failure, an improved nonlinear load-capacity model was introduced. Under the rule of local weighted load redistribution, the influence of weight coeffi-cient, capacity parameters and density of the network on invulnerability of small-world networks against cascading fail-ure was studied by numerical simulation. Then, qualitative analysis of invulnerability of small-world networks under the restrictions of cost and performance was presented. The results demonstrate that, invulnerability of small-world networks weakens with the increasing of the weight coefficient. In addition, the spreading of cascading failure of small-world net-works with different density slows down when the weight coefficient is smaller, and that of the sensitiveness to network density is different. Moreover, there exists an optimal combination of capacity parameters which ensures that small-world networks reach the strongest invulnerability level. Research findings will provide useful guidance and reference in the optimization design of invulnerability for real complex networks.

    Performance analysis of a network coding scheme based on orthogonal process
    2014, 35(6):  2-14. 
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    Combining the orthogonal low-frequency subcarrier processing, a network coding scheme based on orthogonal process (NCOP) was proposed for effective transmission in multi-user multi-relay networks. It makes the data orthogonal before transmission,and decodes the data utilizing the characteristics of orthogonality, so that further reduces the system outage probability and develops the diversity order. The system outage performance and average bit error rate was analyzed by theoretical analysis. Analysis and simulation results show that the system performance of the proposed NCOP outperforms linear network coding while applying in multi-user cooperative networks.
    Fuzzy co-clustering algorithm for high-order heterogeneous data
    2014, 35(6):  3-24. 
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    In order to analyze the clustering results of high-order heterogeneous data at the overlaps of different clusters more efficiently, a fuzzy co-clustering algorithm was developed for high-order heterogeneous data (HFCC). HFCC algorithm minimized distances between objects and centers of clusters in each feature space. The update rules for fuzzy memberships of objects and weights of features were derived, and then an iterative algorithm was designed for the clustering process. Additionally, convergence of iterative algorithm was proved. In order to estimate the number of clusters, GXB validity index was proposed by generalizing the XB validity index, which could measure the quality of high-order clustering results. Finally, experimental results show that HFCC can efficiently mine the overlapped clusters and the qualities of clustering results of HFCC are superior five classical hard high-order co-clustering algorithms. Additionally, GXB validity index can efficiently estimate the number of high-order clusters.
    Strategy of routing based on layered for underwater wireless sensor networks
    2014, 35(6):  4-31. 
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    A layered-depth based routing protocol was proposed for underwater wireless sensor networks (layered-DBR). After nodes broadcast, message only could be received by nodes in predefined depth in order to control the copies of message and finally a network hierarchy model related to redundancy could be built. In this model, the relative depth between nodes and the resident energy of nodes need to be calculated before and after the message forwarding, and then the message forwarding probability can be obtained. A message queue management machanism was established, with which could manage the message's forwarding and history messages, and then the dequeue and enqueue methods were proposed. Compared with DBR and Flooding by simulation, the layered-DBR algorithm can control the network redundancy, reduce the network energy consumption, and prolong the network lifetime.
    Rate control algorithm for no-feedback distributed video coding
    2014, 35(6):  5-38. 
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    In order to address the high requirement of accuracy on rate estimation in the existed bit-plane-level encoder rate control (ERC) methods, a frame-level ERC algorithm was proposed. It used hierarchical fast motion compensated interpolation to obtain high quality side information estimation at the encoder, and removed the difference between bit-planes with cyclic shift to make the coding rates on each bit-plane homogeneous, therefore achieving a frame-level rate control. The simulation results show that compared with the existed methods, the proposed algorithm can improve the quality of side information estimation considerably especially for the middle-high motion video sequences and increase the average PSNR (peak signal-to-noise ratio) of decoded video.
    Seam-Carving forgery detection based on expanded Markov features
    2014, 35(6):  6-46. 
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    To deal with the digital image forgery using Seam-Carving, a detection algorithm based on expanded Markov features was proposed. The algorithm takes full acount of the image frequency domain change caused by Seam-Carving operation, merges the features based on traditional and expands Markov transfer-probability matrix. Trained by SVM, the merged Markov feature can identify the Seam-Carving forgery more effectively. The experiment result shows that the performance of the proposed method is better than that of the method based on traditional Markov features and other existing methods.
    Regular expression matching technology with two-stage memory
    2014, 35(6):  7-55. 
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    To solve the contradiction between the memory requirement and the inspection performance, a matching engine with two-stage memory was proposed for the first time. To deploy the state table to two-stage memory, theories of Markov chain was applied to the FSA. By computing the steady vector, the random access probabilities of each state could be obtained. Further, the states with higher probabilities were deployed in the embedded memory of FPGA, and the states with lower probabilities were deployed in SRAM. Rules in L7-filter were tested in simulation experiments, and the results show that our method can reach a throughput of 33 Gbit/s in large scale FSA, which is 50 times than that of arranging the whole state table in SRAM.
    Multi-path routing protocol based on adaptation mechanism of cell in ad hoc networks
    2014, 35(6):  8-63. 
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    In view of existing ARAS (adaptive response by attractor selection) models’ shortcomings that was noise item produces an effect ambiguously and activity couldn’t determine the opportunity of state changing correctly, an improved ARAS model was proposed. The model specifies the stochastic effect of the noise on the system by an attractor with a noise item. Through putting forward an activity formula inversely proportional to the partial difference between current path status and best path status, it was validated by Matlab with the improved model could increase the accuracy of load balancing in a simple case. A multi-path routing by ARAS mechanism (MPAM) based on AODV is proposed, which selects routing path with the improved ARAS model. Furthermore, the improved model is validated to be able to reduce the average network delay by OPNET.
    Academic paper
    Performance analysis of a network coding scheme based on orthogonal process
    Zu-fan ZHANG,Chun-ling PENG,Jing YANG,Xiao-rong JING
    2014, 35(6):  8-14.  doi:10.3969/j.issn.1000-436x.2014.06.002
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    Combining the orthogonal low-frequency subcarrier processing, a network coding scheme based on orthogonal process (NCOP) was proposed for effective transmission in multi-user multi-relay networks. It makes the data orthogonal before transmission,and decodes the data utilizing the characteristics of orthogonality, so that further reduces the system outage probability and develops the diversity order. The system outage performance and average bit error rate was ana-lyzed by theoretical analysis. Analysis and simulation results show that the system performance of the proposed NCOP outperforms linear network coding while applying in multi-user cooperative networks.

    Scale-free fault-tolerant topology control algorithm in wireless sensor network with optimization of path energy consumption
    2014, 35(6):  9-72. 
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    For the issue of path energy consumption produced in the process of transmitting data in large-scale sensor network, an optimization model of network path energy consumption based on the mode of multi-hop was established, and then the law of obtaining the value of the node degree that could minimize the energy consumption of network was deduced. According to the optimal value of nodes, the network topology was built based on a fitness model which could control the network average node degree, and a scale-free fault-tolerant topology control algorithm EETA(energy efficiency topology algorithm) having the characteristics that could minimize the path energy consumption was put forward. The dynamic performance analysis indicates the network topology which was generated based on this algorithm had the strong fault tolerant ability, because the node degree distribution follows the power-law. The simulation results show that the algorithm also reduces the path energy consumption in the network and then make the network energy-efficient.
    Multi-antenna diversity receiving scheme for mobile communication system in high-speed railway
    2014, 35(6):  10-81. 
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    Under the signal model of differential modulation and demodulation, two multi-antenna diversity receptions (linear combiner and statistic combiner) were proposed, and then the effective diversity reception scheme of train-to-ground wireless broadband communication for high-speed railway scenarios was concluded. Mathematical analysis and simulation results indicate that by increasing the diversity number, the proposals can reduce the error floor because of high mobility. The performance of linear combiner is much better than that of statistic combiner, but the receiver complexity of linear combiner is also higher than that of statistic combiner. In term of practical application, the tradeoff between performance and complexity must be made according to the quality of service (QoS) requirements.
    Voronoi tessellation and hierarchical model based texture image segmentation
    2014, 35(6):  11-91. 
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    A regional and statistical based algorithm for texture image segmentation was proposed. The Voronoi tessellation was used for partitioning the domain of an image into sub-regions corresponding to the components of homogenous regions, to which the texture image needs to be segmented. Bivariate Gaussian Markov random field (BGMRF) model, static random field, and potts model were employed to characterize the interactions between two neighbor pixel pairs in a sub-region, and among sub-regions, respectively. Following Bayesian paradigm, a posterior distribution, which models the texture segmentation for a given texture image, was obtained. A metropolis-hastings algorithm was designed for simulating the posterior distribution. Then, texture segmentation was obtained by maximum a posterior (MAP) scheme. The proposed algorithm was tested with both of synthesized and real texture images. The results are qualitatively and quantitatively evaluated and show that the proposed algorithm works well on both of texture images.
    Rearch and implementation of constant beamwidth time-demain beamformer based on Farrow structure
    2014, 35(6):  12-99. 
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    A new constant beamwidth time-domain beamformer based on Farrow structure filter was proposed, which consists of a digital delay unit to achieve time delay of integral times sampling interval, a high-precision fractional delay filter unit implemented by Farrow structure, and an amplitude weighing unit to ensure constant beamwidth. First, principles, features and advantages of the proposed beamformer was analyzed theoretically. Then its validity and superiority was proved via computer simulation. Finally, its good efficiency and practicability in realtime implementation was tested on C6748 DSP.
    Link quality based path delay analysis in wireless sensor networks
    2014, 35(6):  13-109. 
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    The upper bound of the probability of a path meeting the deadline was given based on link quality, of which the time complexity was proved to be exponential. Moreover, the greedy algorithm (RROP) was proposed to maximize the end-to-end packet deliver ratio under a given deadline, considering the quality of each link. The RROP algorithm optimizes the end-to-end packet deliver ratio by setting the maximum number of retransmissions of each link along the path based on the deadline and link quality. It was proved that the proposed method can find the optimal solution in a polynomial time, and with which could achieve an approximate optimal lower bound of the probability for a path meeting the deadline. Finally, the experimental results show that the upper and lower bounds are accurate, and the proposed algorithm can perform 10% better than the traditional method, in terms of energy consumption and delay.
    LRST: searching tree anti-collision algorithm with low-redundancy
    2014, 35(6):  14-116. 
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    During the RFID tag identification process, the tree-based anti-collision algorithms usually incur large amount of redundant data due to an excess of long query commands,which increases the communication overhead. To resolve this problem, a searching tree anti-collision algorithm with low-redundancy on the basis of regressive-style dynamic searching tree algorithm was proposed. In order to reduce the number of queries, a novel query mode was developed, i.e., single query with duo responses. Depending on the most significant collided bit, the collided tags respond in the first or second slot separately. In order to reduce the length of query command, the prefix matching circuit in tag was replaced with a counter, which eliminated the prefix as the parameter of query command. The predictive identification and blocking technique were also introduced to avoid unnecessary queries. Theoretical analysis and simulation results show that the communication overhead is greatly reduced.
    Blind signal separation algorithm based on temporal predictability and differential search algorithm
    2014, 35(6):  15-125. 
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    A novel blind signal separation algorithm based on differential search was proposed for solving the high calculated amount problem in blind signal separation algorithm based on bio-inspired optimization. The temporal predictability of signal was used as the objective function and the differential search algorithm was used for solving it. The source signal component separated was wiped off using deflation method and all the source signals could be recovered successfully by repeating the separation process. Simulation results show that the algorithm can achieve blind separation from mixed signals efficiently with very high separation precision and very low computing time.
    Academic paper
    Fuzzy co-clustering algorithm for high-order heterogeneous data
    Shao-bin HUANG,Xin-xin YANG,Lin-shan SHEN,Yan-mei LI
    2014, 35(6):  15-24.  doi:10.3969/j.issn.1000-436x.2014.06.003
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    In order to analyze the clustering results of high-order heterogeneous data at the overlaps of different clusters more efficiently, a fuzzy co-clustering algorithm was developed for high-order heterogeneous data (HFCC). HFCC algo-rithm minimized distances between objects and centers of clusters in each feature space. The update rules for fuzzy memberships of objects and weights of features were derived, and then an iterative algorithm was designed for the clus-tering process. Additionally, convergence of iterative algorithm was proved. In order to estimate the number of clusters, GXB validity index was proposed by generalizing the XB validity index, which could measure the quality of high-order clustering results. Finally, experimental results show that HFCC can efficiently mine the overlapped clusters and the qualities of clustering results of HFCC are superior five classical hard high-order co-clustering algorithms. Additionally, GXB validity index can efficiently estimate the number of high-order clusters.

    Blind SINR estimation for OFDM system in the presence of radio frequency interference
    2014, 35(6):  16-131. 
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    Based on cyclostationarity properties of OFDM signal, a novel blind SINR estimation method for OFDM system in the presence of RFI was proposed. By analyzing the power distribution of cyclic correlation of transmitted signal, RFI and AWGN, appropriately selecting the time delay variable and cyclic frequency of the OFDM signal, the signal and interference plus noise power could be efficiently isolated in the power domain, which formed the SINR estimation method. Computer simulation results verify that the performance of the proposed method is superior to that of second-order and fourth-order moments (M2M4) method and the complexity of the new method is also lower than that of the M2M4 method. The new method can also effectively estimate SINR under the fast fading Rayleigh channel. Furthermore, the new method is robust to the density of RFI signal.
    Load balance based relay selection and spectrum transition joint scheme
    2014, 35(6):  17-138. 
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    For load imbalance or hotspot coverage wireless relay network, an adaptive load balance relay selection and spectrum transition joint scheme was proposed. An interference capacity of the stations was also proposed, which reflects the interference to the surrounding co-channel stations. The interference capacity provides a quantitative interference metric to the surrounding stations on the capacity of the system. When a user requires to access the system, the system chooses a preferred access station and an alternative access station for the user according to the channel quality. If the preferred access station is overloaded and does not have enough resources for the user, the performance between accessing to the alternative station and accessing to the preferred station with spectrum transition from other stations in the same sector were compared, and a better way was choosen to maintain the good system performance. The simulation results show that the spectrum efficiency and blocking probability of the proposed scheme in the center cell are superior to that of the independent relay selection scheme and the independent load balance based spectrum transition scheme, and the average interference capacity of the proposed scheme is the lowest, which has less impact on the performance of the surrounding stations.
    Algorithm for foggy image enhancement based on the total variational Retinex and gradient domain
    2014, 35(6):  18-147. 
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    Considering the preservation of color constancy and the improvement of contrast ratio of foggy image enhancement, the foggy image enhancement algorithm based on the total variational Retinex gradient domain method was proposed. Firstly, the algorithm used the GS(Gauss-Seidel)iterative method to resolve the Retinex variational energy functional so that the color constancy was remained and the operational velocity of the proposed algorithm was improved. Secondly, the algorithm stretched strongly the gradient of the higher light blocks in the foggy image by combining the relative gradient and the absolute gradient, and reconstructed the foggy enhancement images with the context of least squares and extended the enhancement method to process the color images. Lastly, the enhancement images by using the total variational Retinex method and the gradient domain algorithm were fused weightedly to keep the color constancy and improve the contrast ratio. The experimental results show that the proposed algorithm can effectively improve the image’s contrast and definition,the algorithm could keep better color constancy and high color fidelity.
    Three-channel dependent mid/side coding framwork for multichannel 3D audio
    2014, 35(6):  19-153. 
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    The conventional mid/side coding method is discussed and generalized to a three-channel dependent M/S coding (3D-M/S) method. Moreover, a codec framework based on 3D-M/S is proposed which enables the 3D-M/S to work for three-dimensional audio systems with more than three channels. It is experimentally shown that proposed framework gets about 25% objective quality improvement compared with independent coding, and only increases about 1/3 complexity of the PCA method.
    Face recognition under unconstrained based on LBP and deep learning
    2014, 35(6):  20-160. 
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    A face recognition method under unconstrained condition was proposed based on deep learning. At the same time, making LBP texture features as the input of deep learning net, and greedy training the network layer was made by layer to obtain good network parameters. At last, the trained net was used to predict the test samples’ labels. The results of experiments on LFW(labeled faces in the wild) show that the algorithm can obtain higher recognition rate than traditional algorithms(such as PCA, SVM, LBP).Otherwise, the recognition rate on Yale and Yale-B are also very high, the experimental results show that deep learning net with LBP texture as its input can classify face images correctly.
    Downlink outage probability analysis of distributed MIMO systems over a composite fading channel
    2014, 35(6):  21-168. 
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    The downlink outage probability of the distributed MIMO systems over a composite channel was discussed. Firstly, a composite fading channel was established by integrating Nakagami-m fading, path loss, and lognormal shadowing. According to the distributed MIMO system with a center-located base station (BS), a quasi-uniform mobile station (MS) distribution model was proposed, which is more suitable for a real communication environment. Next, an approximate analytical expression of average downlink outage probability of the system with arbitrary MS distribution was derived through using mathematical methods such as moment generating function, Gauss-Hermite integral, composite Simpson’s rule and so on. Finally, by taking the proposed MS distribution model into account, the derived closed-form outage probability expression and the MS distribution were proved to be correct and reasonable by computer simulation results.
    Key techniques of cognitive convergence networks
    2014, 35(6):  22-179. 
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    Concentrating on the development of heterogeneous cellular networks and cognitive radio networks, the cognitive cellular networks, femtocell and WiFi 2.0 networks were firstly summarized, respectively. The promising combination potentials of them motivates to define the newly-form networking architecture termed as the cognitive convergence network. In addition, two cognition loops of cognitive resource management and cognitive interference management were proposed to mitigate the intra-tier and inter-tier interference. These cognition loops can help to improve the end-to-end quality of user experience. Finally, the future development and the key techniques of the presented the cognitive convergence networks was looked forward.
    3-subset meet-in-the-middle attack on block cipher TWIS
    2014, 35(6):  23-184. 
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    To do further analysis of the security of lightweight block cipher TWIS, 3-subset meet-in-the-middle attack was applied to 10-round TWIS without the final whitening. Based on the weakness in the key schedule of TWIS:its actual key size was only 62-bit and the confusion speed of the initial key was rather slow, the time complexity to recover the whole 62-bit key of 10-round TWIS was 245, and the data complexity was low enough with only one known plaintext-ciphertext pair. The result shows that block cipher TWIS is not secure under 3-subset meet-in-the-middle attack.
    Improved sub-band JND model with textural decomposition and its application in perceptual image coding
    2014, 35(6):  24-191. 
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    In order to improve the accuracy of the just noticeable difference (JND) model in transform domain, an enhanced JND model with a new method for contrast masking factor estimation was proposed. The image was decomposed and the textural image was used for an accurate block classification, thus the accurate JND in DCT domain was obtained. The improved JND model was applied on the perceptual image coding. Considering the compatibility and the auxiliary information which would affect the encoding efficiency, the JND model was adjusted to the quantization process and removed more visual redundancy. Experimental results show that the proposed algorithm can improve the JND threshold; compared with JPEG standard, the perceptual coding method can save more bit rate and does not need extra bit for auxiliary information at the similar visual quality. The proposed algorithm is also applicable to the perceptual video coding.
    Novel method for joint parameter estimation based on FPSD in wideband bistatic MIMO radar system
    2014, 35(6):  25-199. 
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    A novel algorithm to jointly estimate parameters based on the fractional power spectrum density (FPSD) was proposed in wideband bistatic MIMO radar system. In many applications, it is not appropriate to approximate the wideband signal by the narrowband model, so a novel wideband signal model was proposed to accurately estimate parameters of moving targets. Doppler stretch and time delay are estimated by searching the peak of the fractional power spectrum density (FPSD). Two subarrays are constructed based on the peak of the FPSD. Both direction of departures (DOD) and direction of arrivals (DOA) of the multiple targets are jointly estimated by employing the FPSD-MUSIC algorithm and FPSD-ESPRIT algorithm. Furthermore, the cramér-rao bound (CRB) for target parameters estimation of wideband signal model was derived. Simulation results are presented to verify the effectiveness of the proposed method.
    Academic paper
    Strategy of routing based on layered for underwater wireless sensor networks
    Jian PENG,Chang-jian HONG,Tang LIU,GYun-yong ZHAN
    2014, 35(6):  25-31.  doi:10.3969/j.issn.1000-436x.2014.06.004
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    A layered-depth based routing protocol was proposed for underwater wireless sensor networks (layered-DBR). After nodes broadcast, message only could be received by nodes in predefined depth in order to control the copies of message and finally a network hierarchy model related to redundancy could be built. In this model, the relative depth be-tween nodes and the resident energy of nodes need to be calculated before and after the message forwarding, and then the message forwarding probability can be obtained. A message queue management machanism was established, with which could manage the message's forwarding and history messages, and then the dequeue and enqueue methods were proposed. Compared with DBR and Flooding by simulation, the layered-DBR algorithm can control the network redundancy, re-duce the network energy consumption, and prolong the network lifetime.

    Construction of a new class of (2k, k, 1) convolutional codes
    2014, 35(6):  26-206. 
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    A new class of (2k,k,1) convolutional codes are created by combining double cyclic codes and (2,1,1) convolutional codes, and also a new method for creation long codes with short ones was proposed. The structural mechanism of the codes was revealed by defining a state transition matrix and using algebraic method as well as grille graph. This code structure was excellent in both proportionality and diversity, besides, the distance characteristics of it are also quite well. Simulation results show that, the (2k,k,1) convolutional codes present some advantages over the traditional one in error correction performance and decoding speed.
    Academic paper
    Rate control algorithm for no-feedback distributed video coding
    HENJian C,Chao HUI,Yong-hong KUO
    2014, 35(6):  32-38.  doi:10.3969/j.issn.1000-436x.2014.06.005
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    In order to address the high requirement of accuracy on rate estimation in the existed bit-plane-level encoder rate control (ERC) methods, a frame-level ERC algorithm was proposed. It used hierarchical fast motion compensated interpolation to obtain high quality side information estimation at the encoder, and removed the difference between bit-planes with cyclic shift to make the coding rates on each bit-plane homogeneous, therefore achieving a frame-level rate control. The simulation results show that compared with the existed methods, the proposed algorithm can improve the quality of side information estimation considerably especially for the middle-high motion video sequences and in-crease the average PSNR (peak signal-to-noise ratio) of decoded video.

    Seam-Carving forgery detection based on expanded Markov features
    Guo-rui SHENG,Tie-gang GAO,Li FAN,Lin GAO,Fu-sheng YANG,Shun ZHANG
    2014, 35(6):  39-46.  doi:10.3969/j.issn.1000-436x.2014.06.006
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    To deal with the digital image forgery using Seam-Carving, a detection algorithm based on expanded Markov features was proposed. The algorithm takes full acount of the image frequency domain change caused by Seam-Carving operation, merges the features based on traditional and expands Markov transfer-probability matrix. Trained by SVM, the merged Markov feature can identify the Seam-Carving forgery more effectively. The experiment result shows that the performance of the proposed method is better than that of the method based on traditional Markov features and other existing methods.

    Regular expression matching technology with two-stage memory
    Shu-hui CHEN,Cheng-cheng XU
    2014, 35(6):  47-55.  doi:10.3969/j.issn.1000-436x.2014.06.007
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    To solve the contradiction between the memory requirement and the inspection performance, a matching en-gine with two-stage memory was proposed for the first time. To deploy the state table to two-stage memory, theories of Markov chain was applied to the FSA. By computing the steady vector, the random access probabilities of each state could be obtained. Further, the states with higher probabilities were deployed in the embedded memory of FPGA, and the states with lower probabilities were deployed in SRAM. Rules in L7-filter were tested in simulation experiments, and the results show that our method can reach a throughput of 33 Gbit/s in large scale FSA, which is 50 times than that of ar-ranging the whole state table in SRAM.

    Multi-path routing protocol based on adaptation mechanism of cell in ad hoc networks
    Wei-bing GONG,Xiao-long YANG,Min ZHANG,Ke-ping LONG
    2014, 35(6):  56-63.  doi:10.3969/j.issn.1000-436x.2014.06.008
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    In view of existing ARAS (adaptive response by attractor selection) models' shortcomings that was noise item produces an effect ambiguously and activity couldn't determine the opportunity of state changing correctly, an improved ARAS model was proposed. The model specifies the stochastic effect of the noise on the system by an attractor with a noise item. Through putting forward an activity formula inversely proportional to the partial difference between current path status and best path status, it was validated by Matlab with the improved model could increase the accuracy of load balancing in a simple case. A multi-path routing by ARAS mechanism (MPAM) based on AODV is proposed, which se-lects routing path with the improved ARAS model. Furthermore, the improved model is validated to be able to reduce the average network delay by OPNET.

    Scale-free fault-tolerant topology control algorithm in wireless sensor network with optimization of path energy consumption
    Hao-ran LIU,Tao HAN,Ya-qian LI,Rong-rong YIN
    2014, 35(6):  64-72.  doi:10.3969/j.issn.1000-436x.2014.06.009
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    For the issue of path energy consumption produced in the process of transmitting data in large-scale sensor network, an optimization model of network path energy consumption based on the mode of multi-hop was established, and then the law of obtaining the value of the node degree that could minimize the energy consumption of network was deduced. According to the optimal value of nodes, the network topology was built based on a fitness model which could control the network average node degree, and a scale-free fault-tolerant topology control algorithm EETA(energy effi-ciency topology algorithm) having the characteristics that could minimize the path energy consumption was put forward. The dynamic performance analysis indicates the network topology which was generated based on this algorithm had the strong fault tolerant ability, because the node degree distribution follows the power-law. The simulation results show that the algorithm also reduces the path energy consumption in the network and then make the network energy-efficient.

    Multi-antenna diversity receiving scheme for mobile communication system in high-speed railway
    Wan-tuan LUO,ANGXu-ming F,Meng CHENG,Ya-jun ZHAO
    2014, 35(6):  73-81.  doi:10.3969/j.issn.1000-436x.2014.06.010
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    Under the signal model of differential modulation and demodulation, two multi-antenna diversity receptions (linear combiner and statistic combiner) were proposed, and then the effective diversity reception scheme of train-to-ground wireless broadband communication for high-speed railway scenarios was concluded. Mathematical analysis and simulation results indicate that by increasing the diversity number, the proposals can reduce the error floor because of high mobility. The performance of linear combiner is much better than that of statistic combiner, but the re-ceiver complexity of linear combiner is also higher than that of statistic combiner. In term of practical application, the tradeoff between performance and complexity must be made according to the quality of service (QoS) requirements.

    Voronoi tessellation and hierarchical model based texture image segmentation
    Quan-hua ZHAO,Yu LI,Xiao-jun HE,Wei-dong SONG
    2014, 35(6):  82-91.  doi:10.3969/j.issn.1000-436x.2014.06.011
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    A regional and statistical based algorithm for texture image segmentation was proposed. The Voronoi tessella-tion was used for partitioning the domain of an image into sub-regions corresponding to the components of homogenous regions, to which the texture image needs to be segmented. Bivariate Gaussian Markov random field (BGMRF) model, static random field, and potts model were employed to characterize the interactions between two neighbor pixel pairs in a sub-region, and among sub-regions, respectively. Following Bayesian paradigm, a posterior distribution, which models the texture segmentation for a given texture image, was obtained. A metropolis-hastings algorithm was designed for simulating the posterior distribution. Then, texture segmentation was obtained by maximum a posterior (MAP) scheme. The proposed algorithm was tested with both of synthesized and real texture images. The results are qualitatively and quantitatively evaluated and show that the proposed algorithm works well on both of texture images.

    Rearch and implementation of constant beamwidth time-demain beamformer based on Farrow structure
    Tian ZHOU,Bing-zhi ZHANG,Wei-dong DU,Dong-dong PENG
    2014, 35(6):  92-99.  doi:10.3969/j.issn.1000-436x.2014.06.012
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    A new constant beamwidth time-domain beamformer based on Farrow structure filter was proposed, which consists of a digital delay unit to achieve time delay of integral times sampling interval, a high-precision fractional delay filter unit implemented by Farrow structure, and an amplitude weighing unit to ensure constant beamwidth. First, princi-ples, features and advantages of the proposed beamformer was analyzed theoretically. Then its validity and superiority was proved via computer simulation. Finally, its good efficiency and practicability in realtime implementation was tested on C6748 DSP.

    Link quality based path delay analysis in wireless sensor networks
    Quan CHEN,Hong GAO
    2014, 35(6):  100-109.  doi:10.3969/j.issn.1000-436x.2014.06.013
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    The upper bound of the probability of a path meeting the deadline was given based on link quality, of which the time complexity was proved to be exponential. Moreover, the greedy algorithm (RROP) was proposed to maximize the end-to-end packet deliver ratio under a given deadline, considering the quality of each link. The RROP algorithm optimizes the end-to-end packet deliver ratio by setting the maximum number of retransmissions of each link along the path based on the deadline and link quality. It was proved that the proposed method can find the optimal solution in a polynomial time, and with which could achieve an approximate optimal lower bound of the probability for a path meeting the deadline. Finally, the experimental results show that the upper and lower bounds are accurate, and the proposed algorithm can perform 10% better than the traditional method, in terms of energy consumption and delay.

    LRST: searching tree anti-collision algorithm with low-redundancy
    Qiong HUANG,Jiang-tao LING,Min ZHANG,Xiao-long YANG
    2014, 35(6):  110-115.  doi:10.3969/j.issn.1000-436x.2014.06.014
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    During the RFID tag identification process, the tree-based anti-collision algorithms usually incur large amount of redundant data due to an excess of long query commands,which increases the communication overhead. To resolve this problem, a searching tree anti-collision algorithm with low-redundancy on the basis of regressive-style dynamic searching tree algorithm was proposed. In order to reduce the number of queries, a novel query mode was developed, i.e., single query with duo responses. Depending on the most significant collided bit, the collided tags respond in the first or second slot separately. In order to reduce the length of query command, the prefix matching circuit in tag was replaced with a counter, which eliminated the prefix as the parameter of query command. The predictive identification and block-ing technique were also introduced to avoid unnecessary queries. Theoretical analysis and simulation results show that the communication overhead is greatly reduced.

    Blind signal separation algorithm based on temporal predictability and differential search algorithm
    Lei CHEN,Li-yi ZHANG,Yan-ju GUO,Yong HUANG,Jing-yi LIANG
    2014, 35(6):  117-125.  doi:10.3969/j.issn.1000-436x.2014.06.015
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    A novel blind signal separation algorithm based on differential search was proposed for solving the high cal-culated amount problem in blind signal separation algorithm based on bio-inspired optimization. The temporal predict-ability of signal was used as the objective function and the differential search algorithm was used for solving it. The source signal component separated was wiped off using deflation method and all the source signals could be recovered successfully by repeating the separation process. Simulation results show that the algorithm can achieve blind separation from mixed signals efficiently with very high separation precision and very low computing time.

    Blind SINR estimation for OFDM system in the presence of radio frequency interference
    Shun-li HONG,You-ming LI,Ming JIN,Gang WANG
    2014, 35(6):  126-131.  doi:10.3969/j.issn.1000-436x.2014.06.016
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    Based on cyclostationarity properties of OFDM signal, a novel blind SINR estimation method for OFDM sys-tem in the presence of RFI was proposed. By analyzing the power distribution of cyclic correlation of transmitted signal, RFI and AWGN, appropriately selecting the time delay variable and cyclic frequency of the OFDM signal, the signal and interference plus noise power could be efficiently isolated in the power domain, which formed the SINR estimation method. Computer simulation results verify that the performance of the proposed method is superior to that of sec-ond-order and fourth-order moments (M2M4) method and the complexity of the new method is also lower than that of the M2M4 method. The new method can also effectively estimate SINR under the fast fading Rayleigh channel. Furthermore, the new method is robust to the density of RFI signal.

    Load balance based relay selection and spectrum transition joint scheme
    Bo HUANG,Xu-ming FANG,Yu CHEN,Gao-yong HUANG
    2014, 35(6):  132-138.  doi:10.3969/j.issn.1000-436x.2014.06.017
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    For load imbalance or hotspot coverage wireless relay network, an adaptive load balance relay selection and spec-trum transition joint scheme was proposed. An interference capacity of the stations was also proposed, which reflects the in-terference to the surrounding co-channel stations. The interference capacity provides a quantitative interference metric to the surrounding stations on the capacity of the system. When a user requires to access the system, the system chooses a preferred access station and an alternative access station for the user according to the channel quality. If the preferred access station is overloaded and does not have enough resources for the user, the performance between accessing to the alternative station and accessing to the preferred station with spectrum transition from other stations in the same sector were compared, and a better way was choosen to maintain the good system performance. The simulation results show that the spectrum efficiency and blocking probability of the proposed scheme in the center cell are superior to that of the independent relay selection scheme and the independent load balance based spectrum transition scheme, and the average interference capacity of the proposed scheme is the lowest, which has less impact on the performance of the surrounding stations.

    Algorithm for foggy image enhancement based on the total variational Retinex and gradient domain
    Bing-quan CHEN,Hong-li LIU
    2014, 35(6):  139-147.  doi:10.3969/j.issn.1000-436x.2014.06.018
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    Considering the preservation of color constancy and the improvement of contrast ratio of foggy image en-hancement, the foggy image enhancement algorithm based on the total variational Retinex gradient domain method was proposed. Firstly, the algorithm used the GS(Gauss-Seidel)iterative method to resolve the Retinex variational energy functional so that the color constancy was remained and the operational velocity of the proposed algorithm was improved. Secondly, the algorithm stretched strongly the gradient of the higher light blocks in the foggy image by combining the relative gradient and the absolute gradient, and reconstructed the foggy enhancement images with the context of least squares and extended the enhancement method to process the color images. Lastly, the enhancement images by using the total variational Retinex method and the gradient domain algorithm were fused weightedly to keep the color constancy and improve the contrast ratio. The experimental results show that the proposed algorithm can effectively improve the image's contrast and definition,the algorithm could keep better color constancy and high color fidelity.

    Three-channel dependent mid/side coding framwork for multichannel 3D audio
    Shi DONG,Rui-min HU,Yu-hong YANG,Xiao-chen WANG,Wei-ping TU
    2014, 35(6):  148-153.  doi:10.3969/j.issn.1000-436x.2014.06.019
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    The conventional mid/side coding method is discussed and generalized to a three-channel dependent M/S cod-ing (3D-M/S) method. Moreover, a codec framework based on 3D-M/S is proposed which enables the 3D-M/S to work for three-dimensional audio systems with more than three channels. It is experimentally shown that proposed framework gets about 25% objective quality improvement compared with independent coding, and only increases about 1/3 com-plexity of the PCA method.

    Face recognition under unconstrained based on LBP and deep learning
    Shu-fen LIANG,Yin-hua LIU,Li-chen LI
    2014, 35(6):  154-160.  doi:10.3969/j.issn.1000-436x.2014.06.020
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    A face recognition method under unconstrained condition was proposed based on deep learning. At the same time, making LBP texture features as the input of deep learning net, and greedy training the network layer was made by layer to obtain good network parameters. At last, the trained net was used to predict the test samples' labels. The results of experiments on LFW(labeled faces in the wild) show that the algorithm can obtain higher recognition rate than traditional algorithms(such as PCA, SVM, LBP).Otherwise, the recognition rate on Yale and Yale-B are also very high, the experi-mental results show that deep learning net with LBP texture as its input can classify face images correctly.

    Downlink outage probability analysis of distributed MIMO systems over a composite fading channel
    Wen-jie PENG,Yue-heng LI,Mei-yan JU,Ping HUANG,Guo-ping TAN
    2014, 35(6):  161-169.  doi:10.3969/j.issn.1000-436x.2014.06.021
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    The downlink outage probability of the distributed MIMO systems over a composite channel was discussed. Firstly, a composite fading channel was established by integrating Nakagami-m fading, path loss, and lognormal shad-owing. According to the distributed MIMO system with a center-located base station (BS), a quasi-uniform mobile station (MS) distribution model was proposed, which is more suitable for a real communication environment. Next, an approxi-mate analytical expression of average downlink outage probability of the system with arbitrary MS distribution was de-rived through using mathematical methods such as moment generating function, Gauss-Hermite integral, composite Simpson's rule and so on. Finally, by taking the proposed MS distribution model into account, the derived closed-form outage probability expression and the MS distribution were proved to be correct and reasonable by computer simulation results.

    Overview
    Key techniques of cognitive convergence networks
    Chun-gang YANG,Jian YUE,Jian-dong LI,Min SHENG,Hong-yan LI,Qin LIU
    2014, 35(6):  169-179.  doi:10.3969/j.issn.1000-436x.2014.06.022
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    Concentrating on the development of heterogeneous cellular networks and cognitive radio networks, the cogni-tive cellular networks, femtocell and WiFi 2.0 networks were firstly summarized, respectively. The promising combina-tion potentials of them motivates to define the newly-form networking architecture termed as the cognitive convergence network. In addition, two cognition loops of cognitive resource management and cognitive interference management were proposed to mitigate the intra-tier and inter-tier interference. These cognition loops can help to improve the end-to-end quality of user experience. Finally, the future development and the key techniques of the presented the cognitive conver-gence networks was looked forward.

    3-subset meet-in-the-middle attack on block cipher TWIS
    Ya-fei ZHENG,Hong-ru WEI
    2014, 35(6):  180-184.  doi:10.3969/j.issn.1000-436x.2014.06.023
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    To do further analysis of the security of lightweight block cipher TWIS, 3-subset meet-in-the-middle attack was applied to 10-round TWIS without the final whitening. Based on the weakness in the key schedule of TWIS:its ac-tual key size was only 62-bit and the confusion speed of the initial key was rather slow, the time complexity to recover the whole 62-bit key of 10-round TWIS was 245, and the data complexity was low enough with only one known plain-text-ciphertext pair. The result shows that block cipher TWIS is not secure under 3-subset meet-in-the-middle attack.

    Academic communication
    Improved sub-band JND model with textural decomposition and its application in perceptual image coding
    Ming-kui ZHENG,Kai-xiong SU,Wei-xing WANG,Cheng-dong LAN,Xiu-zhi YANG
    2014, 35(6):  185-191.  doi:10.3969/j.issn.1000-436x.2014.06.024
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    In order to improve the accuracy of the just noticeable difference (JND) model in transform domain, an en-hanced JND model with a new method for contrast masking factor estimation was proposed. The image was decomposed and the textural image was used for an accurate block classification, thus the accurate JND in DCT domain was obtained. The improved JND model was applied on the perceptual image coding. Considering the compatibility and the auxiliary information which would affect the encoding efficiency, the JND model was adjusted to the quantization process and re-moved more visual redundancy. Experimental results show that the proposed algorithm can improve the JND threshold;compared with JPEG standard, the perceptual coding method can save more bit rate and does not need extra bit for auxil-iary information at the similar visual quality. The proposed algorithm is also applicable to the perceptual video coding.

    Novel method for joint parameter estimation based on FPSD in wideband bistatic MIMO radar system
    Li LI,Tian-shuang QIU
    2014, 35(6):  192-199.  doi:10.3969/j.issn.1000-436x.2014.06.025
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    A novel algorithm to jointly estimate parameters based on the fractional power spectrum density (FPSD) was proposed in wideband bistatic MIMO radar system. In many applications, it is not appropriate to approximate the wide-band signal by the narrowband model, so a novel wideband signal model was proposed to accurately estimate parameters of moving targets. Doppler stretch and time delay are estimated by searching the peak of the fractional power spectrum density (FPSD). Two subarrays are constructed based on the peak of the FPSD. Both direction of departures (DOD) and direction of arrivals (DOA) of the multiple targets are jointly estimated by employing the FPSD-MUSIC algorithm and FPSD-ESPRIT algorithm. Furthermore, the cramér-rao bound (CRB) for target parameters estimation of wideband signal model was derived. Simulation results are presented to verify the effectiveness of the proposed method.

    Construction of a new class of (2k, k, 1) convolutional codes
    Cheng-chang ZHENG,Wan-quan PENG,Bo WEI
    2014, 35(6):  200-206.  doi:10.3969/j.issn.1000-436x.2014.06.026
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    A new class of (2k,k,1) convolutional codes are created by combining double cyclic codes and (2,1,1) convolu-tional codes, and also a new method for creation long codes with short ones was proposed. The structural mechanism of the codes was revealed by defining a state transition matrix and using algebraic method as well as grille graph. This code structure was excellent in both proportionality and diversity, besides, the distance characteristics of it are also quite well. Simulation results show that, the (2k,k,1) convolutional codes present some advantages over the traditional one in error correction performance and decoding speed.

Copyright Information
Authorized by: China Association for Science and Technology
Sponsored by: China Institute of Communications
Editor-in-Chief: Zhang Ping
Associate Editor-in-Chief:
Zhang Yanchuan, Ma Jianfeng, Yang Zhen, Shen Lianfeng, Tao Xiaofeng, Liu Hualu
Editorial Director: Wu Nada, Zhao Li
Address: F2, Beiyang Chenguang Building, Shunbatiao No.1 Courtyard, Fengtai District, Beijing, China
Post: 100079
Tel: 010-53933889、53878169、
53859522、010-53878236
Email: xuebao@ptpress.com.cn
Email: txxb@bjxintong.com.cn
ISSN 1000-436X
CN 11-2102/TN
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