• Current Issue
  • Online First
  • Archive
  • Most Downloaded
    Select AllDeselectExport
    Display Method:
    2020,32(6):909-916, DOI: 10.3979/j.issn.1673-825X.2020.06.001
    Abstract:
    In the outdoor non-line-of-sight (NLOS) environment, obstacles prevent the terminal electromagnetic signal from propagating directly to the base station, and under this condition, the location information collected by single base station is insufficient, resulting in low positioning accuracy. In order to solve the above problems, this paper proposes a scattering area model based on spatial layout and a location algorithm based on parameter clustering. The scattering areas are determined according to the spatial layout near the fixed base station and the scattering area model is constructed. Based on this model, the algorithm collects the measurement parameters of multipath signals, effectively combines k-means clustering and mean shift clustering algorithm to cluster the parameters, and then establishes equations according to the clustering results and the geometric structure of the single station positioning system. Finally, the solution problem of the system of equations is transformed into a nonlinear optimization problem, and the Lewenberg-Marquardt (LM) algorithm is used to solve the optimization problem to estimate the target position. Simulation results show that the algorithm can effectively improve the accuracy of location results under the condition that only a single base station is provided in outdoor NLOS environment.
    2020,32(6):917-924, DOI: 10.3979/j.issn.1673-825X.2020.06.002
    Abstract:
    Sparse code multiple access (SCMA) is considered as a promising technique for improving spectral efficiency. we apply SCMA to wireless multicast communication with the purpose of taking the advantage of SCMA to expand multicast capacity.Firstly, we formulate the capacity of the multicast systems;Secondly, we exploit layered coding scheme in the SCMA systems which is no longer constrained by the user with the worst channel quality in the multicast group; Finally, multicast resource allocation algorithm for the SCMA systems is optimized with the objective of maximizing the capacity of the systems. In order to reduce the computational complexity of optimal question, a fast suboptimal algorithm (FSA) is proposed by separating the power allocation and codebook assignment. Simulation results show that the performance of SCMA systems with FSA is better than the performance of orthogonal frequency division multiple access (OFDMA) systems with FSA. The proposed algorithm significantly outperforms conventional multicast (CM) scheme in SCMA systems and OFDMA systems.
    2020,32(6):925-933, DOI: 10.3979/j.issn.1673-825X.2020.06.003
    Abstract:
    This paper proposes a full-duplex cellular subscriber cooperative D2D communication mechanism in cellular networks. Full-duplex cellular subscribers use power domain superposition as a cooperative relay for D2D user pair without direct link, supporting uplink transmission and D2D communication concurrency. The achievable rate domain of the system is analyzed, and a power allocation algorithm based on the max-min achievable rate is proposed. The simulation results show that the achievable rate domain of the system expands with the improvement of self-interference cancellation performance, the achievable rate domain of full-duplex cooperative D2D communication is better than that of half-duplex cooperative D2D communication, and there is an achievable rate tradeoff between the cellular uplink and cooperative D2D link.The proposed power allocation algorithm can dynamically adjust the transmission power and power allocation factor of cellular subscriber according to the channel state, and the power efficiency is higher.Moreover,with the increase of maximum transmit power, the achievable rate of cellular uplink and cooperative D2D link tends to be the same, which can meet the maximum minimum criterion and take into account the fairness between cellular uplink and cooperative D2D link.
    2020,32(6):934-944, DOI: 10.3979/j.issn.1673-825X.2020.06.004
    Abstract:
    Terminal management-control refers to effective control of communication terminals through third-party devices without being attached to operators and users. To solve the problems of high cost and long delay,this paper proposes long term evolution (LTE) management-control schemes including full coverage management-control and target terminal management-control for different scenarios.Based on the principle of LTE terminal timing synchronization, synchronization guidance signal is sent to the terminal to complete the adsorption of the terminal. Tracking area update rejection signaling and attachment rejection signaling are constructed. According to different core network information carried by signaling, LTE terminal full coverage control and target terminal control are realized respectively. The experimental results show that the proposed full coverage control scheme can block all LTE terminals within the coverage of virtual base station from communicating with the outside world, and reduce the control cost.Compared with the traditional LTE target terminal management and control technology,the advantage of target terminal management and control scheme is that it cannot only reduce the control delay, but also complete the detection of the identity information of the target user and block the communication between the target LTE terminal including the voice over long term evolution (volte) terminal and the outside world.
    2020,32(6):945-953, DOI: 10.3979/j.issn.1673-825X.2020.06.005
    Abstract:
    Non-orthogonal multiple access (NOMA) and cognitive radio technology are considered to be the two most promising techniques of the new generation mobile communication system for improving spectral efficiency. In this paper, to optimize the efficiency of the power domain NOMA cognitive radio network, a sub-user power allocation model is established to meet the minimum system throughput and the maximum interference of the main user. Then, the sub-channel throughput formula is decomposed to obtain the sub-channel power allocation coefficient and sub-channel power consumption rate. For the first problem, the objective function is equivalent to two convex function difference forms by using the difference of convex (DC) programming algorithm, and the non-convex problem is transformed into the convex optimization problem by using the first-order Taylor expansion continuous approximation, to obtain the optimal power distribution coefficient of the sub-user of the subchannel multiplexing. To solve the second problem, Dinkelbach, subgradient algorithm and Lagrange function are used to obtain the optimal subchannel power consumption rate. The simulation results show that the proposed power allocation algorithm has fast convergence speed and low time complexity, and its average system energy efficiency performance is far better than the fractional power allocation algorithm.
    2020,32(6):954-960, DOI: 10.3979/j.issn.1673-825X.2020.06.006
    Abstract:
    The underwater non-imaging optical Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) communication system adopts intensity modulation-direct detection method without the frequency and phase components. The beams of different light sources superimpose each other at the receiving end, so the channel correlation is strong and the bit error rate (BER) is high. In order to solve this problem, a precoding algorithm based on MIMO-OFDM received signal Euclidean distance is proposed.Assuming that the transmitter anticipates the channel state information,the optimal precoding matrix is solved under the constraints of non-negative optical signal and limited total power,and the minimum Euclidean distance of the received signal is maximized by allocating different power to different light sources. The transmitting end of the system precodes the signal through the precoding matrix, and the receiving end decodes the received signal which maximizes the Euclidean distance by the maximum likelihood method. The simulation results show that compared with the optical MIMO precoding algorithm based on singular value decomposition (SVD), the proposed algorithm can reduce the BER of the non-imaging optical MIMO-OFDM system under the premise of constant total power.
    2020,32(6):961-968, DOI: 10.3979/j.issn.1673-825X.2020.06.007
    Abstract:
    In the Tanner graph of low density parity check (LDPC) code, there is a kind of structure called trapping set whose uncorrected variable nodes may not be corrected through iteration. In this paper, we will introduce a novel coding and decoding scheme of generalized LDPC codes with the assistance of quadratic residue code. In this scheme, by using quadratic residue code and sacrificing a bit of rate, some variable nodes will be selected to be given the additional protection, hoping that this scheme would help weaken the effects of trapping sets and improve the performance of the original LDPC codes. In the simulation, after counting uncorrected bits and analyzing the related error location histogram, we find that some bits or variable nodes may incline to be wrong. For this result, we figure out its reason from the perspective of trapping set, and select these variable nodes to construct the generalized LDPC codes. From our simulation, this scheme mitigates the error floor of some LDPC codes effectively.
    2020,32(6):969-975, DOI: 10.3979/j.issn.1673-825X.2020.06.008
    Abstract:
    In order to solve the problem that noise and signal interference have an effect on the channel estimation of receiver, the channel estimation method based on integrated neural network has been proposed in this thesis. Firstly, improved neural network will be used to extract nonlinear relationship between pilot signal with noise and original pilot signal. Then the diversity factor will be calculated based on its output errors, and the integrated neural network model will be obtained according to diversity factor. Finally, channel estimation results can be obtained by model. Compared with the LS estimation, not only can this method improve the reliability of the communication, but also reduce the cost of pilot to improve the effectiveness of communication. Under different modulation methods, when the bit error rate is the same, the signal-to-noise ratio (SNR) of LS algorithm is lower; based on orthogonal frequency division multiple (OFDM), the signal-to-noise ratio (SNR) of LS algorithm is lower. The simulation results of OFDM communication system show that the method has good performance.
    2020,32(6):976-983, DOI: 10.3979/j.issn.1673-825X.2020.06.009
    Abstract:
    In order to solve the problems of insufficient notch depth and weak stopband suppression ability of ultra-wideband filter with notch bands, a compact ultra-wideb and filter with dual notched bands is proposed in this paper. The design of the new multi-mode resonator couples with the input and output feeder to complete the design of ultra-wideband filter, and two open-circuit stubs are loaded at the input feeder, and the ultra-wideband filter with dual notched bands is realized. The pass band of the filter is 2.42~10.98 GHz, and the in-band insertion loss is small. Two notch bands are generated at 5.31 GHz and 8.1 GHz respectively, which effectively blocks the interference of narrow-band signal in wireless local area network and X-band satellite communication band to ultra-wideband communication system. The filter is not only simple in structure, but also has outstanding out-of-band suppression (-66.28 dB) and enough notch depth (-39.71~-35.12 dB). At the same time, it satisfies the requirements of ultra-wideband system for insertion loss and return loss of the filter.
    2020,32(6):984-990, DOI: 10.3979/j.issn.1673-825X.2020.06.010
    Abstract:
    Artificial Intelligence (AI) is a great invention of human society. With the development of information technology, AI technology has attracted extensive attention and becomes the hot issue in recent academic research fields. Firstly, the paper introduces three times rise and two times fall of the development history of AI based on the concept of AI.Meanwhile, it also emphasizes that AI has entered a critical period of development in which there are many scientific issues that need to be solved urgently. Then, the two eras of AI 1.0 and 2.0 which cannot be replaced by each other are explained in this paper. To solve practical problems more efficiently and accurately, perhaps the best method is to effectively combine the technical of the two eras. Subsequently, what artificial intelligence does and how it works are explained, and it points out that the role of AI is to help the development of traditional industries and promote the rapid transformation of industrial economy. Finally, this paper analyzes mathematics education from the perspective of AI, and emphasizes that mathematics is the soul of AI. At the same time, the development of AI is expected to promote mathematics education, but the effect has not been truly reflected so far. The application of new technology in education requires constant exploration and practice in the field of subject education.
    2020,32(6):991-102, DOI: 10.3979/j.issn.1673-825X.2020.06.011
    Abstract:
    Action detection becomes a research hotspot in video analysis due to its broad application prospects in autonomous driving, video surveillance, etc. In recent years, methods based on deep learning have made great progress in the field of action detection, and have attracted the attention of researchers at home and abroad. This paper summarizes these methods comprehensively. Firstly, the definition and challenges of the action detection task are introduced. Then, we classify relevant literature carefully from two aspects:temporal action detection and spatio-temporal action detection. The ideas, advantages, and disadvantages of different methods in each category are comprehensively analyzed. Additionally, we introduce some methods based on hot technologies such as weakly supervised learning, graph convolutional network,attention mechanism.Some of the most commonly used datasets and metrics are listed and the performances of the typical methods are compared on these datasets. Finally, we summarize the problems to be solved in the future and some directions worthy of attention for action detection community.
    2020,32(6):1003-1011, DOI: 10.3979/j.issn.1673-825X.2020.06.012
    Abstract:
    Land surface temperature (LST) is a key parameter to describe the process of surface-atmosphere interaction and reflect the surface condition. However, due to the constraints of the imaging conditions of the thermal infrared sensor, there is a contradiction in the spatial and temporal resolution of the remote sensing images. This contradiction prevents the LST data being fully utilized. The LST downscaling algorithm can effectively resolve the contradiction of spatiotemporal resolution, and obtain LST images with higher spatiotemporal resolution. The LST downscaling model is gradually studied from the global model to the local model. In the current studies, the linear relationship between the surface temperature and the auxiliary parameters is considered, however, the local nonlinear relationship is ignored. This study proposed a new algorithm based on the non-linear geographically weighted regression (NL-GWR) model to downscale the LST. This study selects the proper research area,and selects Normalized Difference Vegetation Index (NDVI), Normalized Difference Build-up Index (NDBI) and digital elevation model (DEM) respectively as an auxiliary parameters,this study proposed an LST downscaled model to downscale spatial resolution of the moderate resolution imaging spectroradiometer (MODIS) LST data from 1 000 to 100 m, and analyzed the LST downscaling results, and the results of downscaling based on geographic weighted regression (GWR) model and NL-GWR model were compared and analyzed. The experimental results show that under the same parameters, the NL-GWR model considering the nonlinear relationship is better than the GWR linear model, and the lowest root mean square error (1.96 ℃) and mean absolute error (1.63 ℃).
    2020,32(6):1012-1022, DOI: 10.3979/j.issn.1673-825X.2020.06.013
    Abstract:
    Aiming at how to create a deformation canonical form which can effectively represent the 3D shape,maintain the isometric invariance during the large-scale deformation process, and preserve the geometric details of the original 3D shape, a calculation of 3D shape deformation canonical form based on the accelerated multidimensional scaling algorithm (Accelerated MDS) is proposed in this paper.First,a tetrahedral mesh containing volume information of 3D shape is generated to avoid distortion caused by volume changes during deformation. Second, the farthest point sampling (FPS) algorithm is used to sample the vertices on the original shape, and then the Accelerated MDS algorithm is used to calculate the square geodesic distance matrix, and obtain the spectral embedding coordinates of the original shape through matrix decomposition. Finally, based on the idea of 3D shape registration, the input tetrahedral mesh is deformed according to the initial canonical form by establishing the energy function to calculate the optimal solution. Thus, the deformed shape which retains the geometric details of the input shape is obtained. The experimental results show that taking tetrahedral mesh shape as input, based on the initial canonical form calculated by the Accelerate MDS algorithm, through the minimization of the 3D shape registration energy function, a deformation canonical form which retains more geometric details of the original shape can be obtained. Compared with the existing algorithms, our algorithm is more suitable for calculating deformation canonical form of 3D shape with complex geometric structures and gets more natural shape deformation results with higher universality.
    2020,32(6):1023-1030, DOI: 10.3979/j.issn.1673-825X.2020.06.014
    Abstract:
    Aiming at the problem of spoofing attack in face information authentication system, this thesis proposes a face detection algorithm by using information loss characteristic in color space transformation. Gabor filter banks are used to enhance the texture features of face images in multi-scale and multi-direction. Gauss Radial Basis Function Classifier classifies the feature descriptors extracted by SURF operator, and distinguishes face living objects and the spoofing attacks of illegal users. The inter-class variance, intra-class variance and separability criterion J of the original image features and texture enhanced features are calculated by using the inter-class variance to measure the separability before and after the feature improvement. Finally, the algorithm is tested in public data dataset Replay-Attack and CASIA-FASD. After the enhancement of the color texture image, the key features of the face are enhanced and the general features are suppressed. The variance between the background and the target is increased, and the intra-class variance is reduced. Feature separability is enhanced to be more robust,allowing texture details to be effectively utilized.. The experimental results show that the proposed algorithm can effectively judge the human face and spoofing attacks in real time.
    2020,32(6):1031-1038, DOI: 10.3979/j.issn.1673-825X.2020.06.015
    Abstract:
    In order to solve the problem that the traditional single image restoration algorithm is not ideal, the existing theory uses the condition of information complementarity between multiple images to recover a single image through multiple degraded images on the basis of image registration. It is more popular to use M-estimation to register images, and then use L1 norm for image fusion, which improves the robustness of image restoration, but its convergence speed is not ideal. In order to realize the fast convergence of the algorithm, an image restoration algorithm based on conjugate gradient descent (CGD) is proposed by exploring the improvement of the search gradient direction of the descent algorithm. On this basis, the CGD image restoration algorithm is improved. The difference information between the pre-estimated and post-estimated values is used to optimize the search direction during iteration, that is, the difference between the first and second estimation values is added to the later search gradient, so as to increase the search gradient value and further shorten the iteration time to the minimum value. The simulation results show that the convergence speed of the improved algorithm is faster than that of the image restoration algorithm based on the fastest gradient descent (BGD).
    2020,32(6):1039-1047, DOI: 10.3979/j.issn.1673-825X.2020.06.016
    Abstract:
    In order to accurately extract the road edge in front of the intelligent vehicle in a variety of road environments, an approach of road edge detection based on 3D LIDAR is proposed. The algorithm firstly uses the random sampling consistency algorithm to quickly segment the road area, filter out most of the non-ground data, and improve the processing speed of the subsequent steps. An extraction algorithm based on the unrelated graph neighborhood relationship is proposed, which is characterized by multi-feature, wide-threshold and multi-level curb feature, to improve the accuracy of the roadside detection by setting a variety of roadside geometric features and wider thresholds. Then the candidate points of road edge are obtained by bidirectional scanning line search algorithm. Clustering analysis and denoising are carried out according to the characteristics of density and global continuity of road edge. Finally, the road edge is fitted by quadratic curve.The results show that the algorithm can effectively identify the structural straight and curved road edges under the occlusion of vehicles, pedestrians and obstacles. The accuracy of the algorithm is higher than 86%, and the detection road width error is less than 0.19 m, which verifies the robustness and accuracy of the algorithm.
    2020,32(6):1048-1057, DOI: 10.3979/j.issn.1673-825X.2020.06.017
    Abstract:
    Two-dimensional coupled map lattice (2D CML) model has quite complex dynamic behavior. Its maximum Lyapunov exponent (MLE) is only determined by the local chaotic map. Therefore, a piecewise logistic map (PLM) with much larger Lyapunov exponent (LE) value is selected as the local mapping function of the 2D CML model. According to the independence hypothesis experiment, it is proved that the 2D CML model is intended to obey independent and identical distribution under certain conditions. With the parallel compressed sensing, a compressed sensing measurement matrix is generated by the 2D CML model, and the original image is sampled by compressed sensing measurement matrix. The image is encrypted by processing and multi-round diffusion of the sampled image, and the performance of the encrypted image is analyzed experimentally. Experiments show that the image compression encryption scheme based on 2D CML model has good encryption performance and application prospects.
    2020,32(6):1058-1064, DOI: 10.3979/j.issn.1673-825X.2020.06.018
    Abstract:
    In practical applications of traditional attribute based encryption scheme, it is difficult to track the malicious user who sells his private keys. And, the user attributes can’t show the level of identity. To solve the problem, a weighted attribute-based encryption scheme with traitor tracing is proposed. In the scheme, the user’s private key which contains the user identity information is used to trace traitors. In addition, the idea of attribute weight is adopted, and the attribute set is transformed into the segmentation set of attribute weight through the attribute set segmentation algorithm. The proposed scheme provides fine-grained and flexible access control based on linear secret sharing. It is proved to be secure against chosen plaintext attack under the q-decisional bilinear diffie-hellman assumption in the standard model. Compared with other related schemes, it has significant improvement in communication and computing cost, and it is more suitable for the application of mobile terminal in cloud computing.
    2020,32(6):1065-1074, DOI: 10.3979/j.issn.1673-825X.2020.06.019
    Abstract:
    Among the existing chaotic image encryption algorithms, there are problems such as low system security, inability to resist plaintext attacks, independent of encrypted images, and low efficiency.A multi-image encryption algorithm based on the hyper-chaotic system is proposed.The hyperchaotic system is used to generate chaotic pseudo-random sequences with excellent performance, and multiple images of the same size are combined into one image. Then a series of novel encryption operations are taken to complete the image encryption process.This algorithm introduces plaintext interference terms and involves bit-level rows and columns scrambling,the randomization of DNA,and fast scrambling and spreading operation of DNA. The interference term can be automatically retrieved during decryption with avoidance of the OTP(one-time pad) mode, which makes chaotic random sequences safe and reusable. The simulation and analysis show that the iteration times of chaotic sequences are reduced, the high correlation between images is ensured and the distribution of bit information in plaintext is hidden. The algorithm has good security and can meet the basic requirements of image encryption.
    2020,32(6):1075-1080, DOI: 10.3979/j.issn.1673-825X.2020.06.020
    Abstract:
    An output-feedback discrete sliding mode control based on unbiased state estimation is proposed for industrial control systems under actuator attack and measurement noisy. In the presence of actuator attack, an equivalent sliding mode control law is constructed. Since the attack signal and the state of the system are unknown, an unbiased state observer is introduced to provide the minimum variance unbiased estimator of the system real state from the sensor measurement data subject to noise interference. In order for the designed robust sliding mode control algorithm to be implemented, a one-step delay attack estimation is introduced to obtain the approximate estimate of attack. The convergence of the sliding surface and the bounded stability of the closed-loop system under the proposed control algorithm is proved. Numerical simulation results demonstrate the effectiveness of the unbiased state estimator, and show that compared with the traditional sliding mode control method, the proposed output feedback sliding mode control algorithm has better suppression for the actuator attack and can effectively improve the robustness of the system.
    2020,32(6):1081-1087, DOI: 10.3979/j.issn.1673-825X.2020.06.021
    Abstract:
    The artificial bee colony (ABC) algorithm is a global search algorithm with powerful search capabilities. However, this algorithm uses a one-dimensional search and a greedy search strategy, which causes its convergence speed slower. The traditional ABC algorithm uses hiring bees, observing bees and scouting bees to cooperate with each other. Although each bee has a different division of labor, there is no difference between different types of bees. This paper proposes an artificial bee colony algorithm that improves performance through intelligent search and special partitioning. In this algorithm, different hire bees and observation bees use different search strategies to find food sources. In addition, we abandoned the greedy selection algorithm and updated the location of the food source on each iteration. In this case, the algorithm can use the experience of the entire bee colony to guide the bee’s search. And we prove its effectiveness through the experimental results of a series of benchmark algorithms.
    2020,32(6):1088-1098, DOI: 10.3979/j.issn.1673-825X.2020.06.022
    Abstract:
    Based on the analysis of the development direction and demand of intelligent coal mine, the overall structure of intelligent mine based on perception layer,transmission layer, data layer, platform layer, application layer and display layer is proposed and designed. The geographic information technology, data base and data fusion technology, collaborative processing technology, Internet of things and intelligent sensor,virtualization technology involved in the construction process of intelligent mine are discussed And cloud computing technology.The design method of mine intelligent management and control platform is proposed,including the whole mine intelligent monitoring system, safety production execution system, enterprise management system, intelligent decision analysis system and three-dimensional transparent mine system. The results show that the efficiency of command and dispatch decision is improved, the intuitionistic and operability of information display of mine operation platform is enhanced. Furthermore, through intelligent conference system, the information exchange speed is accelerated, the work efficiency is improved, and the administrative cost is reduced, which provides a new reference for the construction of intelligent mine.
    Select AllDeselectExport
    Display Method:
    Select AllDeselectExport
    Display Method:
    2008,20(6):682-685, DOI: 10.3979/j.issn.1673-825X.2008.06.013
    [Abstract] (1378) [HTML] (0) [PDF 1.61 M] (24836)
    Abstract:
    In order to reduce the interference of wireless communication and to realize the multi-system sharing and transmitting receiving sharing for multi-wireless communication systems, the antenna must work under broadband and different frequency. In this paper, a novel dual-band microstrip antenna with good performance is analyzed and designed, and this antenna has been simulated by using the software HFSS 10.0. The simulation result shows that the frequency channels of the antenna are 1.67~1.84 GHz and 2.33~2.53 GHz, and the relative bandwidths of the antenna are 9.71% and 8.23%, respectively. This antenna can be used in RF communication as a multi frequency antenna.
    2008,20(5):624-626, DOI: 10.3979/j.issn.1673-825X.2008.05.029
    [Abstract] (1116) [HTML] (0) [PDF 1.11 M] (7243)
    Abstract:
    Traveling salesman problem (TSP) is of important theoretical and practical significance and applied widely in engineering practice. The genetic algorithm, ant colony algorithm and simulated annealing were adopted to solve the traveling salesman problem, and the Chinese traveling salesman problem was chosen to simulate. Through the comparison of these three algorithms' advantages and disadvantages, their different applications were gained: the ant colony algorithm is suitable for slow and accurate solving, the simulated annealing applies to quick and accurate solving, and the genetic algorithm is for quick but low accurate solving.
    2012,24(3):319-325, DOI: 10.3979/j.issn.1673-825X.2012.03.010
    [Abstract] (1634) [HTML] (0) [PDF 1.68 M] (5747)
    Abstract:
    Scanning mechanisms and recognizing process of remote electrical tilt antenna are analyzed, and property and type of remote electrical tilt antenna device searching algorithm is concluded, and 4 feedback states of devices in a scan cycle are summarized and the coping methods are presented, so to provide theoretical basis for an algorithm to improve and optimize the device searching efficiency. Layered analysis method to the various searching depth is taken in the algorithm realization and the impacts on the total scanning time with different number of the devices and mask shift bits are researched, and design method of more optimized algorithm is achieved, and device searching algorithm based on repeated scanning and the hybrid mask shift bits on AISG2.0 protocol is put forward. Simulation and practice show that the proposed algorithm can effectively reduce RET device recognition time and increase device search efficiency.
    2010,22(4):395-399, DOI: 10.3979/j.issn.1673-825X.2010.04.001
    [Abstract] (3140) [HTML] (0) [PDF 1.08 M] (4561)
    Abstract:
    In 3GPP LTE (long term evolution) physical layer protocol, Both CQI (channel quality indicator) and HARQ-ACK (hybrid automatic repeat request acknowledgement) adopted a method called super code based on Reed-Muller. It is similar to the encoding of TFCI (transport format combination indicator) in TD-SCDMA physical layer protocol. But the coding matrix used more complex interleaver technology and increased more masks in 3GPP LTE. It made receiver s decoding difficult. According to the characteristics of coding matrix, this paper used FHT (fast Hadamard transformation) and gave an effective decoding algorithm of Reed-Muller. Simulation results show the effectiveness of the algorithm, which has been applied to LTE-TDD wireless integrated test instrument.
    2013,25(1):30-38, DOI: 10.3979/j.issn.1673-825X.2013.01.005
    [Abstract] (2472) [HTML] (36) [PDF 2.62 M] (4534)
    Abstract:
    Distributed storage system introduces redundancy to increase reliability, and erasure code is used widely in distributed storage system. When a node fails in the distributed storage system, a new node is introduced to repair the failed one. When using erasure code, repairing the failed node often requires a large amount of data transfer. Regenerating Code was proposed to reduce the cost of repair bandwidth. Regenerating Code reduces the amount of data uploaded by each helping node by transferring a linear combination of the data it stores to the failed node in the repair process. In this paper we first review the basic idea of regenerating code. Then we summarize the code constructions of both the one by one and cooperative regenerating code. At last we talk about the future research direction.
    2010,22(1):112-117, DOI: 10.3979/j.issn.1673-825X.2010.01.025
    [Abstract] (5831) [HTML] (0) [PDF 1.93 M] (4418)
    Abstract:
    Since Mean-Shift (MS) tracking algorithm always loses tracking objects and the particle filter tracking algorithm costs huge computation, a novel two-step multiple targets tracking algorithm was proposed. Firstly, a candidate object was gotten by Mean-Shift (MS) tracking algorithm. Then, the tracking result would be verified by particle filter technique when the object couldn't be traced exactly. Experimental results show that this approach can maintain the efficiency of MS algorithm and the powerful ability of particle filter technique, so it is of high practicability.
    2010,22(1):63-70, DOI: 10.3979/j.issn.1673-825X.2010.01.015
    [Abstract] (6585) [HTML] (0) [PDF 893.46 K] (4325)
    Abstract:
    In this paper, vertical handoff algorithm for heterogeneous network was studied through the integration between cellular network and wireless local area network (WLAN). The network-end and user-end parameters affecting algorithm performance were analyzed in detail, including the parameter definition, the range of parameters in different access networks, the relations between different parameters and the normalization problem. According to the parameter effects on handoff algorithm and system performance, these parameters were categorized as handoff conditional parameters, handoff decision parameters and handoff assistance parameters. Based on the parameter classification, a new weight variable handoff algorithm was proposed. This algorithm adopts the weights that are adaptive to the characteristics of user traffic, user mobility model and user preference to access networks. Compared with existing vertical handoff algorithms with fixed weights, this novel algorithm takes into account user characteristics and QoS requirements, and it is able to improve user satisfaction level and system performance.
    2010,22(2):174-178, DOI: 10.3979/j.issn.1673-825X.2010.02.011
    [Abstract] (2504) [HTML] (0) [PDF 1.54 M] (4285)
    Abstract:
    High data speed and capacity in LTE makes the contradiction between spectrum resources and business capacity more outstanding. This paper first introduces the robust header compression (ROHC) and its application in PDCP sublayer in 3G system. Then, the paper analyses the process and the principles of implementation. Combined with the process of PDCP header compression, the framework realization of ROHC procedure was discussed separately from compress part and decompress part. Finally, an improved decompression algorithm was put forward to enhance the robustness, especially for great quantity of packet loss.
    2010,22(6):703-707, DOI: 10.3979/j.issn.1673-825X.2010.06.003
    [Abstract] (2093) [HTML] (0) [PDF 1.66 M] (3948)
    Abstract:
    Terahertz(THz) lies between far-infrared and microwave in electromagnetic spectrum with frequency form 0.1 to 10 THz. Terahertz is believed to be the master technology of international electronics and information science, and to be the bridge between micro-electronics and macro wavelength. THz contains great prospect in the electronic, information, life, national defense, aerospace, etc, and has formed a worldwide research climax. This article introduces the main character,primary researchs and applications of Terahertz.
    2012,24(4):411-415, DOI: 10.3979/j.issn.1673-825X.2012.04.004
    [Abstract] (2103) [HTML] (0) [PDF 993.83 K] (3927)
    Abstract:
    In this paper, we introduce a relay to the SISO symmetric wireless interference network, and apply interference alignment technology to this network. By comprehensively considering all the users' performances, we propose an optimized distributed interference alignment algorithm based on the biggest chordal distance criterion. Applying the optimization algorithm, we can realize interference alignment only requiring two time slots extension for the three users SISO interference network, and achieve 1/2 Degree of freedom for each user. Simulation results justify that using relay and optimization algorithm can significantly improve the capacity and energy efficiency of the system.
    2009,21(3):432-434, DOI: 10.3979/j.issn.1673-825X.2009.03.022
    [Abstract] (5853) [HTML] (0) [PDF 1.19 M] (3764)
    Abstract:
    The attitude arithmetic is one of the important parts in strapdown inertial navigation system (SINS). Based on traditional three order recursive Taylor expansion and four-order Range-Kuttle method, another effective method four-order Taylor expansion was proposed. Under the typical circular cone rotation condition, the three algorithms were simulated on angle error. Considered precision and speed, the simulation result proves that the four-order recursive Taylor expansion is better than the three-order recursive Taylor expansion and the four-order Range Kuttle method. And this method offers reference for developing attitude arithmetic of SINS.
    2010,22(2):131-134, DOI: 10.3979/j.issn.1673-825X.2010.02.002
    [Abstract] (5318) [HTML] (0) [PDF 1.45 M] (3718)
    Abstract:
    Timing error sensitivity is the characteristic of orthogonal frequency division multiplexing (OFDM) system. Using superimposed training sequence, a novel weak power training sequence was proposed. The training sequence, superimposed on the cyclic prefix, has lower power than the reduplicate structure training sequence. The method can reduce the bit error rate of the system affected by the superimposed training sequence. It can make the sidelobe of the correlation lower and improve the timing synchronization accuracy by using the structural characteristic. The timing synchronization accuracy using the structure proposed at the low SNR is higher than that of the reduplicate structure. The performance of the method is checked by simulation.
    2009,21(6):704-709, DOI: 10.3979/j.issn.1673-825X.2009.06.002
    [Abstract] (6398) [HTML] (0) [PDF 1.63 M] (3678)
    Abstract:
    Based on the 3GPP long term evolution (LTE) Release 8 standard released recently, the mechanism of designing and realizing radio link control (RLC) acknowledged mode(AM) transmission mode in LTE radio protocol stack was studied. The structure of air interface protocol stack in LTE radio access network was introduced, then the design principle of RLC AM transmission mode was analyzed, and a method was proposed to realize the AM transmission mode in LTE air interface protocol stack software based on 3GPP standard.
    2008,20(2):194-196, DOI: 10.3979/j.issn.1673-825X.2008.02.014
    Abstract:
    The design method of a dual-section transmission line transformer with broadband is studied. This transformer can achieve the ideal impedance matching between two arbitrary frequencies. In ideal conditions, all parameters can be obtained by solving the equations which are satisfied with the transformer. If using the optimization designed by Ansoft Designer, the broadband impedance transformer can be gained. Simulation results verify the validity of the design.
    2013,25(1):101-110, DOI: 10.3979/j.issn.1673-825X.2013.01.017
    [Abstract] (2041) [HTML] (24) [PDF 1.31 M] (3408)
    Abstract:
    Traditional classification methods are based on the assumption that the training sets are well-balanced, however, in real case the data is usually unbalanced, and the classification performance of the traditional classification is always restricted. A detailed overview of domestic and foreign classification algorithms from the data level and algorithm level is provided in this paper. And through simulation experiments to compare the classification performance of a variety of unbalanced classification algorithm on six different data sets, it is found that the improved classification algorithm has varying degrees of improvement for overall performance. The paper concludes with a list of problems which need solving for the development of unbalanced data classification.
    2008,20(2):132-138, DOI: 10.3979/j.issn.1673-825X.2008.02.002
    Abstract:
    Gaussian minimum shift keying (GMSK) is a constant envelope modulation with continuous phase, and achieves good power-bandwidth efficiency. According to the basic principle of GMSK signal, the GMSK demodulation based on Viterbi algorithm and its performance analysis are presented by describing the signal state and the computation of the branch metric in trellis diagram. Simulation result indicates that the proposed algorithm possesses good performance of anti-noise and anti-multipath. And it can obtain 7 dB gains under the same condition of bit error rate of 10-3 than that of the 2-bits differential demodulation.
    2009,21(4):518-522, DOI: 10.3979/j.issn.1673-825X.2009.04.013
    [Abstract] (4197) [HTML] (0) [PDF 470.98 K] (3180)
    Abstract:
    Computer forensics is an important method for solving civil dispute and fighting against computer crime. Hence, it is valuable to realize computer forensics by utilizing intelligent information processing technology. The development and problems for intelligent forensic technologies were discussed from the angle of formal forensic analysis method, user behavior analysis, intelligent image forensic and intelligent video forensic. Future trends of intelligent forensic technology were analyzed.
    2013,25(1):24-29, DOI: 10.3979/j.issn.1673-825X.2013.01.004
    [Abstract] (2427) [HTML] (31) [PDF 2.23 M] (3155)
    Abstract:
    The OpenFlow network, which separates the control plane from the data plane, provides a real platform for innovation in the Internet. The working processes of the OpenFlow switch are analyzed, and the performance of the PC-based OpenFlow switch is measured and analyzed too. The experimental results depict that no matter for the TCP or the UDP packet transmitting, the PC-based OpenFlow switch can have a good performance in the moderate scale OpenFlow network. However, the throughput will decline rapidly when lots of short packets arrive at the switch. And the flow entries constructing for the high-speed UDP packets will depress the performance of the OpenFlow network too.
    Abstract:
    For improving the convergence performance of antennas beamforming algorithms, this paper proposes a new MIMO-SDMA of smart antennas beamforming algorithm based on research of optimization vector value of phase-amplitude perturbations by improved Memetic algorithm. Simulation results show that this algorithm has good convergence performance and convergence efficiency; the system based on the algorithm can adjustably suppress interferers by placing nulls at the directions of the interfering sources and provide a maximum main lobe in the direction of the desired signal at the same time; thus, the signal to interference ratio of the system is increased, and the uplink MIMO-SDMA can be achieved.
    2012,24(4):420-425, DOI: 10.3979/j.issn.1673-825X.2012.04.006
    [Abstract] (1999) [HTML] (0) [PDF 1.81 M] (3038)
    Abstract:
    In this paper, the impacts of mutual coupling on the performance of MIMO wireless channel are analyzed. From the analysis of the antenna model by network equivalent analysis, the impedance matrix and the mutual coupling matrices of transmitter and receiver are obtained. A general expression of the spatial correlation between a pair of mutually coupled antennas is explicitly derived, and the conditions under which mutual coupling has no effect on the spatial correlation are also identified. The effects of mutual coupling on the parallel antenna array and the collinear antenna array are investigated. Simulation results show that the impacts of mutual coupling on parallel antenna array and collinear antenna array are quite different in the performance of MIMO channel, and the performance of MIMO system affected by mutual coupling can be improved effectively by properly selecting antenna array.

DownloadMore+

    News & AnnouncementsMore+

      External Links

      Peer review

      WeChat

      Mobile website