Long L.,Xi'an University of Technology |
Zhanhui W.,Wuhan Naval University of Engineering |
Qijun S.,China Electronic Systems Engineering Corporation |
Haiyan Z.,Xinjiang Oilfiled Company Exploration and Development Research Institute
Proceedings - 4th International Congress on Image and Signal Processing, CISP 2011 | Year: 2011
The boundary macroblock padding is one key technology of MPEG-4 codes. In MPEG-4, the repetitive padding algorithm does not make use of the trend of pixel value variation often near object boundaries in padding the exterior pixels of reference video object. In this paper, in order to improve performance of MPEG-4 coder, a linear padding for MPEG-4 motion estimation is proposed to reduce prediction errors and improve compression efficiency. In our test, the different video rate distortion curves verify that the proposed algorithm get the higher PSNR (0.4∼2.5 dB) than the repetitive padding scheme does at different bit rate. © 2011 IEEE.
Wang H.,Nanjing University of Science and Technology |
Lu Z.-Y.,China Electronic Systems Engineering Corporation |
Yang L.,China Institute of Technology
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics | Year: 2016
Direct sequence spread spectrum (DSSS) can suppress interference to a certain extend in satellite communication. However, because the spreading gain is limited, when strong interference is more than the system interference tolerance margin, the system transmission performance would be reduced sharply. The technology of transform domain signal processing could detect and suppress interference in the DSSS, so it could improve the anti-interference ability of the system. Wavelet packet transform which has the excellent time-frequency local analysis ability, is very suitable for interference detection and suppression in the DSSS system. The regular wavelet packet decomposition and the best wavelet packet decomposition are studied, and a new method for interference suppression based on the best wavelet packet decomposition is proposed, which combines subband power ratio and the minimum power threshold to location and suppress interference. The simulation results show that the proposed algorithm enhances the performance and anti-interference ability of the system greatly, increases the computational complexity slightly, compared to that based on regular wavelet packet decomposition and the traditional fast Fourier transformation (FFT) algorithm. It is a more effective method to suppress interference in the satellite DSSS communication system. © 2016, Editorial Office of Systems Engineering and Electronics. All right reserved.
Yang Y.,Beijing University of Posts and Telecommunications |
Liu Q.,Beijing University of Posts and Telecommunications |
Gao Z.,Beijing University of Posts and Telecommunications |
Qiu X.,Beijing University of Posts and Telecommunications |
And 2 more authors.
Eurasip Journal on Wireless Communications and Networking | Year: 2015
An efficient data dissemination mechanism is very critical for traffic safety and inquiring path information. All vehicles go straight and do not consider the effect of traffic lights during its running in the motorway. But in view of characteristic of motorway, the fast moving of vehicles will cause the frequent changes of network topology, which is a challenge for data dissemination for motorway environment in Vehicular ad hoc networks (VANETs). This paper proposes a novel data dissemination mechanism for VANETs which apply to broadcasting and on-demand unicast scenarios. We firstly propose a weighted K-nearest neighbors prediction algorithm with self-feedback to predict the current speed of a vehicle and construct a set of forwarders for emergency message broadcasting. To satisfy users’ personal demands, the paper also designs a unicast mechanism based on information urgent level and the improved Greedy Perimeter Stateless Routing (GPSR) protocol. The simulation results show that our proposed method can achieve better performance with higher delivery ratio, lower number of forwarders, and less copies of messages. © 2015, Yang et al.
Qi F.,Beijing University of Posts and Telecommunications |
Li Q.,Beijing University of Posts and Telecommunications |
Han Q.,Beijing University of Posts and Telecommunications |
Du Y.,China Electronic Systems Engineering Corporation |
Qiu X.-S.,Beijing University of Posts and Telecommunications
Beijing Youdian Daxue Xuebao/Journal of Beijing University of Posts and Telecommunications | Year: 2014
An improved BP neural network algorithm based on dichotomy was proposed for assessment of electric power communication network risk. The dichotomy was used to adjust the learning rate in the training process. It helps to change the learning rate automatically to the direction of optimization. Simulation shows that the improved algorithm's performance is optimized, such as convergence rate, error accuracy and training time.
Ren T.,University of Chinese Academy of Sciences |
Ren T.,CAS Institute of Computing Technology |
Ren T.,China Electronic Systems Engineering Corporation |
Fu J.,University of Chinese Academy of Sciences |
And 2 more authors.
Gaojishu Tongxin/Chinese High Technology Letters | Year: 2015
In order to improve the performance of a virtual machine's interpreter under the non-uniform memory access (NUMA) architecture, a study of memory access optimization was conducted. Then, a scheme for memory optimization of the interpreters under the NUMA architecture was proposed, and based on it, two novel approaches for an interpreter's memory optimization, namely the one using static instruction dispatching and another using dynamic instruction dispatching, were designed and implemented. According to the scheme, the virtual machine collects the information of the NUMA nodes when it starts up, and automatically generates all the data structures the interpreter needs in each NUMA node; when the interpreter is running on a NUMA node, it uses the two mentioned dispatching optimization approaches to realize its local access to the NUMA nodes. The experimental results demonstrated that the proposed scheme can significantly improve the performance of interpreters in NUMA systems. The results of the experiment using the DaCapo showed that the overall performance of the interpreter was improved by 8%, and the highest increment was up to 23%. The proposed memory optimization algorithm is very easyto implement and can be applied to most NUMA systems. © 2015, Inst. of Scientific and Technical Information of China. All right reserved.
Lin Y.,PLA Air Force Aviation University |
Liang J.,PLA Air Force Aviation University |
Zhao H.,PLA Air Force Aviation University |
Wang S.,China Electronic Systems Engineering Corporation |
Niu X.,PLA Air Force Aviation University
Yadian Yu Shengguang/Piezoelectrics and Acoustooptics | Year: 2015
A novel UWB antenna yields an impendence bandwidth of 2.0-10.6 GHz is designed in this paper, supposed to fulfill many requirements such as small size, wide working bandwidth, ominidirectional radiation patterns. A novel, feasibility method used for band-notched characteristics is demonstrated and the equivalent circuit for this method is proposed. Simulated and measured results all show that the UWB antenna yields an impendence bandwidth of 2.0-10.6 GHz by defining VSWR 2. Based on this method, a extremely narrow notch band at 5.0-5.90 GHz is realized by adding a patch connected with the radiation patch by a via hole, covering the operating band of WLAN((5.125-5.85 GHz). And it improves the quality of WLAN communication links in UWB environment, realizing spectrum compatibility. © 2015, Sichuan Institute of Piezoelectric and Acoustooptic Technology. All right reserved.
Liu L.,Xi'an University of Technology |
Liu L.,Xi'an Jiaotong University |
Song Q.-J.,China Electronic Systems Engineering Corporation |
Zhao T.-F.,Xi'an University of Technology |
Yuan X.-H.,Xi'an Jiaotong University
Tongxin Xuebao/Journal on Communications | Year: 2013
The spacial and temporal character of motion vector were analysed and according to the spacial and temporal characteristic of motion vector, the different proposed search schemes were adopted for motion estimation; The experimental results shows the proposed algorithm reduce the prediction error and has a significant computational speedup compared with other algorithms, but offers a similar, even better performance.
Li X.-L.,National University of Defense Technology |
Wang H.-M.,National University of Defense Technology |
Guo C.-G.,China Electronic Systems Engineering Corporation |
Ding B.,National University of Defense Technology |
And 3 more authors.
Journal of Zhejiang University: Science C | Year: 2012
Network virtualization is recognized as an effective way to overcome the ossification of the Internet. However, the virtual network mapping problem (VNMP) is a critical challenge, focusing on how to map the virtual networks to the substrate network with efficient utilization of infrastructure resources. The problem can be divided into two phases: node mapping phase and link mapping phase. In the node mapping phase, the existing algorithms usually map those virtual nodes with a complete greedy strategy, without considering the topology among these virtual nodes, resulting in too long substrate paths (with multiple hops). Addressing this problem, we propose a topology awareness mapping algorithm, which considers the topology among these virtual nodes. In the link mapping phase, the new algorithm adopts the κ-shortest path algorithm. Simulation results show that the new algorithm greatly increases the long-term average revenue, the acceptance ratio, and the long-term revenue-to-cost ratio (R/C). © 2012 Zhejiang University and Springer-Verlag Berlin Heidelberg.
Zhu L.,PLA University of Science and Technology |
Chen J.,PLA University of Science and Technology |
Zhao Y.,PLA University of Science and Technology |
Zhao Y.,China Electronic Systems Engineering Corporation
IET Conference Publications | Year: 2010
A novel cross-layer scheduling algorithm with guaranteed QoS is proposed in CRN. A distinct scheduling priority integrating UCSI, QSI and QoS requirements is first proposed for CUs. Base on these scheduling priorities and specific scheduling mechanism, packet scheduling and channel allocation are jointly designed. The simulation results reveal that the proposed algorithm suffers a limited decline in system throughput while reduces the packet delay and packet dropping probability effectively for cognitive users. By the optimized channel assignment with the Channel Allocation Weight, a better performance for spectral utility, packet delay and packet dropping probability is obtained under the dynamic UCSI in CRN.
Chen L.,PLA University of Science and Technology |
Song Z.,PLA University of Science and Technology |
Zhang Y.,PLA University of Science and Technology |
Zhou N.,China Electronic Systems Engineering Company
Journal of Software | Year: 2012
Measures of similarity between two terms or concepts have been widely used in the domain of Natural Language Processing, Semantic Web, and so on. There are mainly two kinds of methods for measuring similarity. One is based on prior manually built taxonomy or Ontology; the other which is usually referred to as the statistical approaches is based on the corpus. However, the ontology-based method has problem of coverage and the corpus-based method has the problem of sparse data. In order to overcome these problems, a huge data source World Wide Web was used to calculate similarity between concepts. The concept similarity was measured using the association rule mining in the snippets returned from Web search engines. The most influential algorithm for association rule mining is Apriori. In order to improve the efficiency of Apriori algorithm and use it to measure the concept similarity, there are three main improvements in Apriori algorithm. The experimental result shows that the algorithm can improve the precise of measuring concept similarity. © 2012 Academy Publisher. © 2012 Academy Publisher.