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Hopping control channel MAC protocol for opportunistic spectrum access networks

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The Journal of china Universities of Posts and telecommunications 2010年第6期17卷 65-71页

作者： FU Jing-tuan,JI Hong,MAO Xu Key laboratory of Universal wireless Communications,Ministry of Education,beijing university of Posts and {4.,beijing 100876,china [a] Key laboratory of Universal wireless Communications Ministry of Education Beijing University of Posts telecommunications Beijing 100876 China

Opportunistic spectrum access （OSA） is considered as a promising approach to mitigate spectrum scarcity by allowing unlicensed users to exploit spectrum opportunities in licensed frequency bands. Derived from the existing channel-hopping multiple access （CHMA） protocol,we introduce a hopping control channel medium access control （MAC） protocol in the context of OSA networks. In our proposed protocol,all nodes in the network follow a common channel-hopping sequence; every frequency channel can be used as control channel and data channel. Considering primary users＇ occupancy of the channel,we use a primary user （PU） detection model to calculate the channel availability for unlicensed users＇ access. Then,a discrete Markov chain analytical model is applied to describe the channel states and deduce the system throughput. Through simulation,we present numerical results to demonstrate the throughput performance of our protocol and thus validate our work.

关键词： channel hopping MAC protocol OSA Markov chain

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

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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 {4. 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

On-demand coding-aware routing in wireless Mesh networks

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The Journal of china Universities of Posts and telecommunications 2010年第5期17卷 80-86,92页

作者： SUN Jian-zhen,LIU Yuan-an,HU He-fei,YUAN Dong-ming wireless Communications and EMC laboratory,beijing university of Posts and {4.,beijing 100876,china [a] wireless Communications EMC laboratory Beijing University of Posts telecommunications Beijing 100876 China

network coding,which exploits the broadcast nature of wireless medium,is an effective way to improve network performance in wireless multi-hop networks,but the first practical wireless network coding system COPE cannot actively detect a route with more coding opportunities and limit the coding structure within two-hop *** on-demand coding-aware routing scheme （OCAR） for wireless Mesh networks is proposed to overcome the limitations specified above by actively detecting a route with more coding opportunities along the entire route rather than within two-hop *** more coding opportunities tends to route multiple flows ‘close to each other’ while avoiding interference requires routing multiple flows ‘away from each other’.OCAR achieves a tradeoff by adopting RC AIA as routing metric in route discovery,which is not only coding-aware but also considers both inter and intra flow *** results show that,compared with Ad-hoc on-demand distance vecfor routing （AODV） and AODV＋COPE,OCAR can find more coding opportunities,thus effectively increase network throughput,reduce end to end delay and alleviate network congestion.

关键词： Mesh networks network coding coding-aware routing protocol

Performance evaluation of channel inversion precoding for downlink multi-user MIMO system

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The Journal of china Universities of Posts and telecommunications 2009年第5期16卷 20-24页

作者： CHEN Zhi-yong , WANG Wen-bo, PENG Mu-gen, LI Ren wireless Signal Processing and network laboratory, Key laboratory of Universal wireless Communication, Ministry of Education, beijing university of Posts and telecommunications, beijing 100876, china [a]wireless Signal Processing and network laboratory Key laboratory of Universal wireless Communication Ministry of Education beijing university of Posts and telecommunications beijing 100876 china

In downlink multi-user multi-input multi-output （MU-MIMO） system, not every user （user equipment （UE）） can calculate accurately signal to interference and noise ratio （SINR） without prior knowledge of the other users＇ precoding vector. To solve this problem, this article proposes a channel inversion precoding scheme by using the lower bound of S1NR and zero-forcing （ZF） algorithm. However, the SINR mismatch between lower bound SINR and actual SINR causes the inaccurateness of adaptive modulation and coding （AMC）. As a result, it causes degradation in performance. Simulation results show that channel inversion precoding provides lower throughput than that of single user multi-input multi-output （SU-MIMO） at high signal-to-noise ratio （SNR）（〉14.dB）, due to the SINR mismatch, although the sum-rate of channel inversion precoding is higher than that of SU-MIMO at full SNR regime.

关键词： MU-MIMO channel inversion precoding CQI feedback AMC lower bound S1NR zero-forcing

Cooperative HARQ protocol and diversity analysis of systems with multiple incremental relays

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The Journal of china Universities of Posts and telecommunications 2009年第5期16卷 8-13页

作者： FAN Bin , WANG Wen-bo, LIN Yi-cheng, ZHENG Kan wireless Signal Processing and network Lab, Key laboratory of Universal wireless Communication, Ministry of Education, {4. university of Posts and telecommunications, beijing 100876, china [a]wireless Signal Processing and network Lab Key laboratory of Universal wireless Communication Ministry of Education beijing university of Posts and telecommunications beijing 100876 china

wireless networks contain an inherent distributed spatial diversity that can be exploited by relays. Relay networks can take advantage of the broadcast-oriented nature of wireless transmission, but require more radio resource to transmit data for their multi-hop traits. Fortunately, incremental relaying technique, which can choose direct or multi-hop transmission adaptively, can efficiently utilize resource. In this article, the incremental transmission with amplify-and-forward （AF） relays is focused on. A practical hybrid-automatic retransmission request （HARQ） protocol is designed, and the related optimal relay selection strategy is proposed. To analyze the cooperative diversity of system with the proposed protocol, the capacity lower bound is deduced. Simulation and analytical results indicate that by adopting the optimal relay selection strategy, the system with the proposed HARQ protocol can achieve an order of cooperative diversity that equals the aggregated number of the relay and source nodes.

关键词： cooperative HARQ AF incremental relay diversity gain

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

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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,{4. university of Posts and telecommunications,beijing 100876,china 2 School of Information Engineering,North china university of Technology,{4. 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

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

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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 {4.,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

SVM-based loss differentiation algorithm for wired-cum-wireless networks

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The Journal of china Universities of Posts and telecommunications 2009年第4期16卷 104-111页

作者： DENG Qian-hua ,CAI An-ni School of Telecommunication Engineering,beijing university of Posts and telecommunications,beijing 100876,{4. [a]School of Telecommunication Engineering beijing university of Posts and telecommunications beijing 100876 china

In a hybrid wired-cum-wireless network environment, packet loss may happen because of congestion or wireless link errors. Therefore, differentiating the cause is important for helping transport protocols take actions to control congestion only when the loss is caused by congestion. In this article, an end-to-end loss differentiation mechanism is proposed to improve the transmission performance of transmission control protocol （TCP）-friendly rate control （TFRC） protocol. Its key design is the introduction of the outstanding machine learning algorithm - the support vector machine （SVM） into the network domain to perform multi-metric joint loss differentiation. The SVM is characterized by using end-to-end indicators for input, such as the relative one-way trip time and the inter-arrival time of packets fore-and-aft the loss, while requiring no support from intermediate network apparatus. Simulations are carried out to evaluate the loss differentiation algorithm with various network configurations, such as with different competing flows, wireless loss rate and queue size. The results show that the proposed classifier is effective under most scenarios, and that its performance is superior to the ZigZag, mBiaz and spike （ZBS） scheme.

关键词： machine learning SVM TCP-friendly rate control (TFRC) congestion control

Quantum threshold group signature

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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 {4. of Integrated Services network, Xidian university, Xi’an 710071, china 3 State Key {4. of Information Security (Graduate university of Chinese Academy of Sciences), beijing 10004., china 4.State Key {4. 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 100124 China State Key laboratory of Integrated Services network Xidian University Xi’an 710071 China State Key laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing 100049 China State Key laboratory of networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 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