检索结果-南通市图书馆

Toward path reliability by using adaptive multi-path routing mechanism for multimedia service in mobile Ad-hoc network

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of posts and telecommunications 2010年第1期17卷 93-100页

作者： ZHEN Yan,WU Mu-qing,WU Da-peng,ZHANG Qin-juan,XU Chun-xiu Broadband Communication Network Laboratory,beijing university of posts and telecommunications,beijing 100876,China [a] Broadband Communication Network Laboratory Beijing University of Posts telecommunications Beijing 100876 China

Traditional multi-path routing mechanisms aim to establish complete node or link disjoint paths. However, under some circumstances if multiple paths cannot be established based on the current network topology, the traditional multi-path routing mechanism will degenerate into single path routing mechanism, thus the advantages of multi-path routing cannot be exhibited. To enhance the end-to-end path reliability, an adaptive multi-path routing mechanism with path segment is proposed, in which multi-path can be established at part of the end-to-end path. In this way the reliability of the path can be enhanced. This path segment mechanism can divide the end-to-end path into several short segments, and a parallel forwarding mechanism is proposed for guaranteeing the quality of service of multimedia services over the wireless network. Simulations show that the network performance metrics such as the packet delivery ratio, the end-to-end delay and the number of route discoveries are all improved by using the adaptive multi-path routing mechanism.

关键词： mobile Ad-hoc networks multi-path routing reliability parallel forwarding path segment

Research on Three Dimensional Computer Assistance Assembly Process Design System

在线全文

学校读者我要写书评

暂无评论

武汉理工大学学报 2006年第S3期28卷 1088-1092页

作者： HOU Wenjun YAN Yaoqi DUAN Wenjia SUN Hanxu Automation school,beijing university of posts & {4.,beijing 100876,China, Automation school Beijing University of Posts & TelecommunicationsBeijing 100876China

The computer aided process planning will certainly play a significant role in the success of enterprise information- ization.3-dimensional design will promote Tri-dimensional process *** article analysis nowadays situation and prob- lems of assembly process planning,gives a 3-dimensional computer aided process planning system(3D-VAPP),and researches on the product information extraction,assembly sequence and path planning in visual interactive assembly process design,dynamic emulation of assembly and process verification,assembly animation outputs and automatic exploding view generation,interactive craft filling and craft knowledge management,*** also gives a multi-layer collision detect and multi-perspective automatic camera switching *** were done to ualidate the feasibility of such technology and algorithm,which established the foundation of tri-dimensional computer aided process planning.

关键词： assembly craft information extraction collision detect craft plan components position and posture

Data-aided synchronization algorithm dispensing with searching procedures for UWB communications

在线全文

学校读者我要写书评

暂无评论

science China(Information sciences) 2012年第4期55卷 778-788页

作者： REN ZhiYuan 1,JIANG Ting1,ZHONG Yi 2 & ZHAO ChengLin 1 1 Key Laboratory of Universal Wireless Communications,Ministry of Education of China Wireless Network Laboratory,beijing university of posts and telecommunications,beijing 100876,China 2 school of Information Engineering,North China university of Technology,beijing 10004.,China 1. Key Laboratory of Universal Wireless Communications Ministry of Education of China Wireless Network Laboratory Beijing University of Posts and Telecommunications Beijing 100876 China2. School of Information Engineering North China University of Technology Beijing 100041 China

Rapid and accurate synchronization constitutes a major challenge in deploying Ultra-Wideband impulse radio (UWB-IR) for indoor wireless *** paper develops a data-aided (DA) synchro-nization algorithm dispensing with searching procedures for UWB-IR *** adopting a stream of alternating orthogonal pulses,frame-level synchronization can be achieved without channel ***-out utilizing any searching procedure,the timing offset estimator is obtained in a closed *** exhaustive search can be avoided,both computational complexity and synchronization time are *** and comparisons are provided to illustrate the advantages of our design over the alternatives.

关键词： Ultra-Wideband impulse radio synchronization dispensing with searching procedures searching space data-aided estimation

A novel adaptive spectrum forming filter:Application in cognitive ultra-wideband

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science China(Information sciences) 2010年第12期53卷 2584-2599页

作者： LI Bin ,ZHOU Zheng & ZOU WeiXia Key Lab of Universal Wireless Communications,MOE.Wireless Network Lab,beijing university of posts and telecommunications,beijing 100876,China 1. Key Lab of Universal Wireless Communications MOE. Wireless Network Lab Beijing University of Posts and Telecommunications Beijing 100876 China

Ultra wideband impulse radio(UWB-IR) has important applications in high data rate communications,high precision positioning and penetrating target *** with cognitive radio(CR),UWB can also greatly alleviate the current spectrum ***,the existing UWB waveforms are faced with two *** spectrum utilization of UWB signal is rather low,which reduces the communication ***,it appears difficult for UWB-IR to avoid spectrum collision with other incumbent *** UWB will inevitably interfere other legal wireless *** by these considerations,we model the UWB waveform design into an interpolation *** on radial basis function neural network,a novel UWB pulse is presented in this *** UWB pulse is then realized though reasonable simplification on the already proposed theoretical *** designed UWB pulses can adaptively track the external spectral environment where UWB devices work and reconfigure its emission spectrum according to the state of primer users without any modification on *** frequency utilization is maximized when there is no active primary *** adequate spectrum avoidance has also been achieved without much spectrum utilization degradation within the non-primary *** and analysis show that our UWB-IR pulse is much superior to the other existing UWB signals in the frequency utilization,spectrum avoidance and in the transmission performance.

关键词： UWB-IR cognitive radio pulse design RBF network spectrum efficiency spectrum avoidance

A class of discounted models for singular diffusion control

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese science Bulletin 2000年第5期45卷 405-408页

作者： LIU Kunhui, QIN Mingda & LU Chuanlai1. College of sciences, Northern Jiaotong university, beijing 10004., China 2. Department of Mathematics and Mechanics, beijing university of science and Technology, beijing 100083 .China 3. Department of Information Engineering, beijing university of posts and telecommunications, beijing 100876, China Correspondence should be addressed to Lu Chuanlai College of sciences Northern Jiaotong University Beijing China Department of Mathematics and Mechanics Beijing University of Science and Technology Beijing China Department of Information Engineering Beijing University of Posts and Telecommunications Beijing China

A kind of discounted problems for singular diffusion control have been studied. The drift and diffusion coefficients of state process are nonlinear. The class of models has been basically extended from a corresponding one established by Karatzes et al. before. By applying some analysis methods different from earlier works, the sufficient and necessary conditions of the existence of optimal control have been obtained. If an optimal control exists, it is a 'transient reflection' of state process for two lines.

关键词： stochastic control variational equation singular stochastic control.

An improved dynamic user equipment power saving mechanism for LTE system and performance analysis

在线全文

学校读者我要写书评

暂无评论

science China(Information sciences) 2010年第10期53卷 2075-2086页

作者： XU HaiBo, TIAN Hui , HUANG Bo & ZHANG Ping Key Laboratory of Universal Wireless Communications, Ministry of Education beijing university of posts and telecommunications,{4., China 1. Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

In order to minimize the power consumption of user equipments (UEs), and further to support various services and transmissions of large amount of data, the power saving mechanisms have been investigated for most remarkable wireless systems. In this paper, an improved dynamic discontinuous reception (D-DRX) scheme is presented for LTE system, which is able to adaptively adjust the inactivity timer and the sleep period of UEs’ receivers. Moreover, theoretical analysis based on the Markov chain is provided for the D-DRX scheme. Several numerical examples quantitatively show that the D-DRX scheme can capture various packet arrival patterns and scheduling behaviors of system to make a better tradeoff between power saving and packet delay by considering the length of packet queue.

关键词： power saving DRX Markov chain LTE-advanced

Subsection-filtering method applied in optoelectronic signal processing of the liquid drop analyzer

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Subsection-filtering method applied in optoelectronic signal...

Practical conditions of signal space alignment for generalized MIMO Y channel

2010 International Conference on Display and Photonics

作者： HUANG Jia-yong SONG Qing WU Di LIU Jing ZHANG Chun-song Automation school beijing university of posts and {4. beijing 100876 China beijing Univ. of posts and telecommunications (China)

ISBN: (纸本)9780819482402

Liquid drop fingerprint can be obtained through fiber-capacitive drop analysis technology as the fiber signal changes with the drop volume which can be represented by the capacitive signal during the drop ***,if the fiber or capacitive signals are filtered by the normal low-pass filter method,the fingerprint would be distorted because of the capacitive signal’s saw-tooth style and fiber signal’s periodically abrupt *** the paper the subsection-filtering method is explored and analyzed,in which firstly separates the signals according to drop growth period and then filters every subsection *** improves that it is an effective way to solve the signal distortion problem, which usually happens when filters the fiber or capacitive signal during the signal mutation period.

关键词： Fiber-capacitive drop analysis liquid drop fingerprint subsection filter zero-phase filter signal mutation

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

science China(Information sciences) 2012年第10期55卷 2171-2182页

作者： SHE JiaJu 1,2,CHEN ShanZhi 1,2,HU Bo 1,WANG YingMin 2 & SU Xin 2 1 State Key Laboratory of Networking and Switching Technology,beijing university of posts and telecommunications,beijing 100876,China 2 State Key Laboratory of Wireless Mobile Communications,China Academy of telecommunications Technology,beijing 100191,China 1. State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China2. State Key Laboratory of Wireless Mobile Communications China Academy of Telecommunications Technology Beijing 100191 China

This paper proposes a generalization for applications of signal space alignment(SSA) in a generalized multiple input multiple output(MIMO) Y channel with K(K 2) nodes and an intermediate *** on that generalization,a method is introduced to determine the practical conditions for *** first study the generalized MIMO Y channel model with general signal demands;then,the degrees of freedom(DoF) achieved are given and are proved using *** SSA could decrease the number of antennas at the relay,it places new restrictions on the numbers of antennas at the *** then introduce a method to compare the models with and without SSA network coding(SSA-NC),mainly from the perspective of the total number of antennas *** results show that if each node must be able to exchange signals with all others,the model with SSA will definitely use more antennas to supply the same DoF,when K > *** it is not necessary for every node to exchange signals with all others,the comparison can still be made by using the method introduced *** a result,the conditions under which SSA-NC is needed are presented.

关键词： Signal space alignment MIMO Y channel degrees of freedom number of antennas

Performance Analysis of Channel Assignment with Prioritized Handoff Procedures in GSM

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

The Journal of China Universities of posts and telecommunications 2001年第2期8卷 45-50页

作者： WANG Xiao xia, XIN Zhan hong (school of Business, beijing university of posts and telecommunications, beijing 100876, P.R.China) school of Business Beijing University of Posts and Telecommunications

A mathematical model of channel assignment with prioritized handoff procedures is given according to the physical handoff process in GSM networks with some reasonable simplifications and assumptions, and a numerical calculation is applied to the model. A simulation model is established to verify the results of the mathematical model. The results show that the overall loss probability is increased with the number of channel reservation increasing, although the probability of forced termination can be reduced. Therefore, three queuing schemes are proposed: (1) queuing for handoff calls without channel reservation, and the queuing rule is “First come, first served”; (2) queuing for handoff calls without channel reservation, and the queuing rule is “First come to the threshold, first served”; (3) queuing for new calls with one channel reserved for handoff calls. Simulations are also made for the three queuing schemes, the results indicate that the third one is the best, and it is also easy to realize. The optimal queuing length and the maximum waiting time are suggested for the third scheme.

关键词： performance analysis queuing system teletraffic theory GSM handoff channel reservation