检索结果-南通市图书馆

POWER CONTROL STRATEGIES FOR MULTICHANNEL COGNITIVE WIRELESS networkS WITH OPPORTUNISTIC INTERFERENCE CANCELLATION

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Electronics(china) 2008年第2期25卷 268-273页

作者： Tang Zhenzhou Hu Qian Yu Guanding College of Physics and Electronic information Wenzhou University Wenzhou 325000 China zhejiang provincial key laboratory of information network technology Zhejiang University Hangzhou 310027 China

In this letter,an Opportunistic Interference Cancellation(OIC) is first introduced as a rate control strategy for secondary user in cognitive wireless networks. Based on the OIC rate control method,an optimal power control strategy for multichannel cognitive wireless networks is proposed. The algorithm aims to maximize the total transmit rate of cognitive user through appropriately controlling the transmit power of each subchannel under the constraint that the interference temperature at the primary receiver is below a certain threshold. Three suboptimal power control methods,namely Equal Power Transmission(EPT) ,Equal Rate Transmission(ERT) and Equal Interference Transmission(EIT) ,are also proposed. The performances of the proposed power control methods are compared through numerical simulations.

关键词：无线网络干扰温度功率控制干扰取消

Contourlet HMT model with directional feature

在线全文

学校读者我要写书评

暂无评论

Science china(information Sciences) 2012年第7期55卷 1563-1578页

作者： WANG XiangHai 1,2,3 ,CHEN MingYing 1 ,SONG ChuanMing 1,2 ,XU MengChun 1 & FANG LingLing 3 1 College of Computer and information technology,Liaoning Normal University,Dalian 116029,china 2 State key laboratory for Novel Software technology,Nanjing University,Nanjing 210093,china 3 provincial key laboratory for Computer information Processing technology,Soochow University,Suzhou 215006,china College of Computer and information technology Liaoning Normal University Dalian China State key laboratory for Novel Software technology Nanjing University Nanjing China provincial key laboratory for Computer information Processing technology Soochow University Suzhou China

According to Shanno's information theory,the directional feature of texture is defined as the value of directional variable when an image signal attains a singularity of random *** terms of this definition,we calculate the texture's directional features using Tamura's method and study the directional probability distribution of Contourlet *** we find that the directional features tend to be conveyed across parent and child *** on this conclusion,we establish a novel probability distribution model of hidden direction variables under the condition of hidden state variable's distribution,named Contourlet HMT model with directional *** structure and training method of the model are presented as ***,an unsupervised context-based image segmentation algorithm is proposed on the basis of the proposed *** effectiveness is verified via extensive experiments carried out on several synthesized images and remote sensing images.

关键词： directional feature Contourlet HMT Contourlet HMT with directional feature unsupervised texture segmentation

Threshold proxy quantum signature scheme with threshold shared verification

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(Physics,Mechanics & Astronomy) 2008年第8期51卷 1079-1088页

作者： YANG YuGuang1,3,4 & WEN QiaoYan2 1 College of Computer Science and technology,Beijing University of technology,Beijing 100124,china 2 State key laboratory of networking and Switching technology,Beijing University of Posts and Tele-communications,Beijing 100876,china 3 State key laboratory of Integrated Services network,Xidian University,Xi’an 710071,china 4 State key laboratory of information Security(Graduate University of Chinese Academy of Sciences) ,Beijing 100049,china College of Computer Science and technology Beijing University of Technology Beijing China State key laboratory of Integrated Services network Xidian University Xi’an China State key laboratory of information Security (Graduate University of Chinese Academy of Sciences) Beijing China State key laboratory of networking and Switching technology Beijing University of Posts and Telecommunications Beijing China

A threshold proxy quantum signature scheme with threshold shared verification is proposed. An original signer could authorize a group as its proxy signers. Then only t or more of n persons in the proxy group can generate the proxy signature on behalf of the original signer and any t-1 or fewer ones cannot do that. When the proxy signature needs to be verified,any t or more of n persons belonging to the verification group can verify the message and any t-1 or fewer ones cannot verify the validity of the proxy signature.

关键词： quantum signature threshold proxy quantum group signature threshold shared verification

Quantum threshold group signature

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2008年第10期51卷 1505-1514页

作者： YANG YuGuang1,2,3 & WEN QiaoYan4 1 College of Computer Science and technology, Beijing University of technology, Beijing 100124, china 2 State key laboratory of Integrated Services network, Xidian University, Xi’an 710071, china 3 State key laboratory of information Security (Graduate University of Chinese Academy of Sciences), Beijing 100049, china 4 State key laboratory of networking and Switching technology, Beijing University of Posts and Tele-communications, Beijing 100876, china College of Computer Science and technology Beijing University of Technology Beijing China State key laboratory of Integrated Services network Xidian University Xi’an China State key laboratory of information Security Graduate University of Chinese Academy of Sciences Beijing China State key laboratory of networking and Switching technology Beijing University of Posts and Telecommunications Beijing China

In most situations, the signer is generally a single person. However, when the message is written on behalf of an organization, a valid message may require the approval or consent of several persons. Threshold signature is a solution to this problem. Generally speaking, as an authority which can be trusted by all members does not exist, a threshold signature scheme without a trusted party appears more attractive. Following some ideas of the classical Shamir’s threshold signature scheme, a quantum threshold group signature one is proposed. In the proposed scheme, only t or more of n persons in the group can generate the group signature and any t-1 or fewer ones cannot do that. In the verification phase, any t or more of n signature receivers can verify the message and any t-1 or fewer receivers cannot verify the validity of the signature.

关键词： threshold quantum signature trusted party quantum cryptography

Threshold quantum secret sharing between multi-party and multi-party

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2008年第9期51卷 1308-1315页

作者： YANG YuGuang1,2,3 & WEN QiaoYan4 1 College of Computer Science and technology,Beijing University of technology,Beijing 100124,china 2 State key laboratory of Integrated Services network,Xidian University,Xi’an 710071,china 3 State key laboratory of information Security (Graduate University of Chinese Academy of Sciences),Beijing 100049,china 4 State key laboratory of networking and Switching technology,Beijing University of Posts and Tele-communications,Beijing 100876,china College of Computer Science and technology Beijing University of Technology Beijing China State key laboratory of Integrated Services network Xidian University Xi’an China State key laboratory of information Security (Graduate University of Chinese Academy of Sciences) Beijing China State key laboratory of networking and Switching technology Beijing University of Posts and Telecommunications Beijing China

A threshold quantum secret sharing (TQSS) scheme between multi-party and multi-party was proposed using a sequence of single photons,which is useful and efficient when the parties of communication are not all present. We described the process of this TQSS scheme and discussed its security. It was shown that entan-glement is not necessary for quantum secret sharing. Moreover,the theoretic effi-ciency was improved to approach 100% as almost all the instances can be used for generating the private key,and each photon can carry one bit of information. This protocol is feasible with the present-day technique.

关键词： threshold quantum secret sharing quantum cryptography single photon multi-party and multi-party

RST transforms resistant image watermarking based on centroid and sector-shaped partition

在线全文

学校读者我要写书评

暂无评论

Science china(information Sciences) 2012年第3期55卷 650-662页

作者： ZHAO Yao1,2*, NI RongRong1,2* & ZHU ZhenFeng1,2* 1Institute of information Science, Beijing Jiaotong University, Beijing 100044, china 2Beijing key laboratory of Advanced information Science and network technology, Beijing 100044, china Institute of information Science Beijing Jiaotong University Beijing China Beijing key laboratory of Advanced information Science and network technology Beijing China

A novel digital watermarking scheme featuring centroid-based sectoring is proposed in this paper. To get higher robustness against geometric attacks, such as rotation, scaling, and translation (RST), a delicate synchronization mechanism was developed and incorporated into the proposed approach. During the process of watermark embedding, the original image was partitioned into sectors based on the image centroid. Synchronization information as well as the message bits is then embedded into these sectors. With the help of the centroid-based sectoring and synchronization information, the proposed approach is capable of restoring the correct sectoring even if it has experienced severe geometric distortion. This attribute ensures the correct recovery of embedded watermarks and contributes to the robustness of the proposed scheme. A series of experiments have been conducted to verify the feasibility and effectiveness of the proposed approach. Experimental results show that the proposed scheme possesses good robustness against RST attacks and considerable robustness against other common image processing attacks.

关键词： digital watermarking geometrical transform attacks RST transforms

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

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) 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 100041,china key laboratory of Universal Wireless Communications Ministry of Education of China Wireless network laboratory Beijing University of Posts and Telecommunications Beijing China School of information Engineering North China University of Technology Beijing 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

Secure network coding in the presence of eavesdroppers

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3期53卷 648-658页

作者： LUO MingXing1,2,3, YANG YiXian1,2,3, WANG LiCheng1,2,3 & NIU XinXin1,2,3 1information Security Center, State key laboratory of networking and Switching technology, Beijing University of Posts and Telecommunications, Beijing 100876, china 2key laboratory of network and information Attack and Defence technology of MOE, Beijing University of Posts and Telecommunications, Beijing 100876, china 3National Engineering laboratory for Disaster Backup and Recovery, Beijing University of Posts and Telecommunications, Beijing 100876, china information Security Center State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing China key laboratory of network and information Attack and Defence technology of MOE Beijing University of Posts and Telecommunications Beijing China National Engineering laboratory for Disaster Backup and Recovery Beijing University of Posts and Telecommunications Beijing China

Our concern, in the paper, is to construct information-theoretic secure network coding in the presence of eavesdroppers. Based on the generalized attack model and all-or-nothing transformation, the security of network coding in the generalized combination network can be characterized by the network capacity and the min-cut bound of wiretapping set from the source. Furthermore, it can be extended to any directed acyclic networks with single source. Compared with the traditional results, we construct information-theoretic secure network coding without additional encryptions and giving up any capacity.

关键词： all-or-nothing transformation secure network coding eavesdropping

Communication network designing:Transmission capacity,cost and scalability

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) 2012年第11期55卷 2454-2465页

作者： ZHANG GuoQiang1,2,3 & ZHANG GuoQing1 1Institute of Computing technology,Chinese Academy of Sciences,Beijing 100190,china 2School of Computer Science and technology,Nanjing Normal University,Nanjing 210046,china 3provincial key laboratory for Computer information Processing technology,Soochow University,Suzhou 215000,china Institute of Computing technology Chinese Academy of Sciences Beijing China School of Computer Science and technology Nanjing Normal University Nanjing China provincial key laboratory for Computer information Processing technology Soochow University Suzhou China

Despite the growing number of works centering around the traffic dynamics on complex networks,these researches still have some common shortcomings,e.g.,too simple traffic flow model and lack of considerations for the designing cost and scalability *** paper builds on a more realistic traffic flow model,and offers a holistic view on the network designing *** addition to the extensively studied transmission capacity,this paper takes designing cost and scalability as two other designing objectives,and presents a quantitative study of how different designing choices independently and collectively influence these objectives by the introduction of a cartesian coordinate *** is shown that different kinds of network topologies display different shapes of achievable solution spaces and exhibit different abilities to achieve cost-effective and scalable *** particular,we find the philosophy underlying empirical network designing and engineering today fails to meet the cost-effective and scalable designing requirements,and propose a cost-effective and scalable designing scheme for BA-like networks,i.e.,the efficient routing combined with effective betweenness based link bandwidth *** addition,when designing a thoroughly new network from the beginning,we find that ER network is a good candidate to achieve cost-effective and scalable designing in most settings.

关键词： cost-effective communication network designing network transmission efficiency network topology traffic dynamics next generation network scalable network designing