检索结果-南通市图书馆

Cooperative automatic modulation recognition in cognitive radio

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2期17卷 46-52,71页

作者： CHEN Mei zhu qi Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Nanjing 210003 China National Mobile Communications Research Laboratory Southeast University Nanjing 210003 China

In this article, a new effective method of cooperative modulation recognition （CMR） is proposed to recognize different modulation types of primary user for cognitive radio receivers. In the cognitive radio （CR） system, two CR users respectively send their feature parameters to the cooperative recognition center, which is composed of back propagation neural network （BPNN）. With two users＇ cooperation and the application of an error back propagation learning algorithm with momentum, the center improves the performance of modulation recognition, especially when one of the CR users＇ signal-to-noise ratio （SNR） is low. To measure the performance of the proposed method, simulations are carried out to classify different types of modulated signals corrupted by additive white Gaussian noise （AWGN）. The simulation results show that this cooperation algorithm has a better recognition performance than those without cooperation.

关键词： cooperative modulation recognition cognitive radio (CR) feature parameter neural network

Network selection algorithm based on AHP and similarity

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 2018年第2期25卷 77-88,104页

作者： Li Wanghong zhu qi Jiangsu Key Lab of Wireless Communications Nanjing University of Posts and Telecommunications

In heterogeneous wireless networks, there are various kinds of service demands from the users. A network selection algorithm based onthe analytic hierarchy process （AHP） and Similarity is proposed to solve this problem. The services are divided into three classes： Conversational Class, Streaming Class and Interactive Class. According to the characteristics of each service, a different judgment matrix is assigned and then the AHP method is used to calculate the network attribute weights. Taking the dynamic changes in user demands and network environment into account, a formula based on Lance distance for computing the attributes similarity is derived to evaluate the degree of conformity between user requirements and network attributes, from which the similarity between the user requirements and network attributes is calculated and then the total similarity by weighting. The network with the largest total similarity is the best choice. Simulation results demonstrate the effectiveness of the proposed scheme in improving the quality of service （QoS） according to the user requirements under three kinds of services.

关键词： AHP attributes similarity service type network selection

Interference aware routing for mobile ad hoc networks based on node's sending and receiving capabilities

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 2013年第4期20卷 73-79,111页

作者： GU Chao zhu qi Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Key Lab on Wideband Wireless Communications and Sensor Network Technology of Ministry of Education Nanjing University of Posts and Telecommunications

How to efficiently build routes among nodes is increasing important for mobile ad hoc networks （MANETs）. This paper puts forward an interference aware routing protocol called Interference aware cross layer routing protocol （IA-CLR） for MANETs based on the IEEE 802.11 medium access layer （MAC）. By defining the node＇s sending and receiving capabilities, IA-CLR can indicate the interference strength of the link in a real and comprehensive way. Further more, in order to choose the route with minimum bottleneck link interference, a new routing metric is proposed by combining the MAC layer and the network layer for cross layer design. Simulation results show that IA-CLR can significantly improve the performances of network such as the average end-to-end delay, the packets loss ratio and the throughput.

关键词： ad hoc networks routing protocol routing design interference aware

Energy efficient joint power and subcarrier assignment scheme in OFDM relay system

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 2015年第5期22卷 56-62页

作者： Liang Xuanwei zhu qi College of Telecommunications & Information Engineering Nanjing University of Posts and Telecommunications

A power and subcarrier assignment algorithm is proposed in this paper for maximizing the energy efficiency in the single-relay multi-users orthogonal-frequency-division-multiplexing(OFDM) systems. Under the constraints of maximum total power and minimum transmission rate, we formulate a joint optimization scheme for subcarrier pairing and power allocation to maximize the energy efficiency. The Dinkelbach’s method is used to depress the complexity and to transform the problem to a linear programming, then we use the dual decomposition approach solve the problem. In the premise of the system transmission rate, this algorithm uses the improved decode-and-forward(IDF) relay to maximize the system energy efficiency. Simulation results illustrate that,compared with the spectral-efficient maximization(SEM) algorithm, the energy-efficient maximization(EEM) algorithm proposed in this paper makes the energy efficiency not decline when the signal-to-noise radio(SNR) is at a high level. At the point where SNR is 10 d B and the number of subcarriers is 16, system energy efficiency is increased by 6.2% and 11.9% with the subcarrier pairing strategy and power allocation strategy respectively.

关键词： energy efficiency green communications multi-user

Coalitional game-based WiFi offloading algorithm in heterogeneous networks

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 2019年第4期26卷 25-35页

作者： Sun Lin zhu qi Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and TelecommunicationsNanjing 210003China Engineering Research Center of Health Service System Based on Ubiquitous Wireless Networks Nanjing University of Posts and TelecommunicationsMinistry of EducationNanjing 210003China

Aiming at the coexistence of cellular network and wireless fidelity(WiFi)network,a coalitional game-based WiFi offloading algorithm in heterogeneous networks is ***,this paper defines the user fairness utility function that comprehensively considers the user communication rate,cost and ***,the coalitional game model including two types of coalitions is *** control the transfer of users among coalitions,a coalition transfer criterion that simultaneously improves the user's individual utility and the total system utility is *** addition,this paper presents a channel allocation scheme that ensures full utilization of system resources to maximize the total utility of the *** simulation results show that the proposed offloading algorithm can reasonably utilize the resources of cellular network and WiFi network,and improve the utility of users and system.

关键词： WiFi offloading fairness coalitional game resource allocation

Reconstruction of Industrial Location in View of Industrial Agglomeration

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2006年第4期16卷 294-298页

作者： zhu Huayou ding Sibao College of Tourism and Resources and Management Zhejiang Normal University Jinhua 321004 China College of Urban and Environmental Science Northeast Normal University Changchun 130024 China

The Industrial Agglomeration Theory has been evolving all the time. The study on the industrial location has become the focus of the massive theoretical location problems about agglomeration since the 1970s. The authors here analyze the evolution and the characteristics of the Industrial Agglomeration Theory and study its effect on the reconstruction of industrial location. The study suggests that the new idea ofrecoustmction of industrial location is to cultivate regional innovative system. On this basis, the authors analyze two cases of old industrial bases on their constniction-Tiexi Industrial District in Shenyang City and Changchun Industrial Economic Development Zone. Finally, the authors put forward some suggestions that should be regarded, which include： 1） to combine industrial location reconstruction and enterprises＇ inner reform; 2） to speed up adjustment of resources and opening to the world; 3） to combine government mechanism with the market mechanism properly.

关键词： industrial location industrial agglomeration reconstruction of industrial location old industrial district regional innovation system

SYNTHESIS AND PROPERTIES OF NEW SIDE-CHAIN LIQUID CRYSTALLINE POLYMER WITH LATERALLY ATTACHED MESOGENS BY ESTER GROUP

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 1999年第5期17卷 499-502页

作者： qi-ding Mi qi-feng Zhou Department of Polymer Science&Engineering College of ChemistryPeking UniversityBeijing 100871China

New liquid crystalline monomer,2,5-bis[(4'-methoxyphenoxy)carbonyl]phenyl acrylate was successfully *** with laterally attached mesogens via ei;ter linkage was also *** polymer forms an enantiotropic liquid crystal phase while its monomer exhibits a metastable nematic phase with respect to the crystalline ***,its liquid crystallinity is very low as compared to that of poly{2,5-bis[(4'-methoxyphenoxy)carbonyl]-styrene}.

关键词： poly{2,5-bis[(4'-methoxyphenoxy)carbonyl]phenyl acrylate} hydroxyterephthalic acid mesogen-jacketed liquid crystalline polymers

P-Twisted Affine Lie Algebras and Their Associated Vertex Algebras

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2008年第7期50卷 7-12页

作者： ding Lu ZHENG zhu-Jun Institute of Applied Mathematics Academy of Mathematics and Systems Science the Chinese Academy of Sciences Beijing 100080 China School of Mathematical Sciences South China University of Technology Guangzhou 510641 China Institute of Mathematics Henan University Kaifeng 475001 China

For any finite-dimensional semisimple Lie algebra g, a Z＋-graded vertex algebra is construsted on the vacuum representation Vk（g[θ]of g[θ]）,which is a one-dimentionM central extension of 8-invariant subspace on t... 详细信息

关键词： p-twisted affine Lie algebra vertex algebra

Science Letters:A current-differential-based method for improving dynamic characteristics of electromagnetic actuators

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第9期10卷 1241-1244页

作者： Ping FANG qi-peng LI Fan ding State Key Lab of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China School of Mechanical and Automotive Engineering Zhejiang University of Science and Technology Hangzhou 310023 China

This paper presents a new control strategy based on current differential feedback to accelerate the dynamic response of electromagnetic actuators, instead of traditional closed-loop control based on displacement feedback. The method mainly includes a differentiator, proportioner and signal synthesizer. Analysis and simulation on the step characteristics of an electromagnetic actuator were discussed, and all the results show that the approach can improve the actuator's step response greatly. Finally, the control method is applied to a real gravure system which verifies the control performance.

关键词： Electromagnetic actuator Control method Dynamic characteristics Current differential