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Optimal user scheduling and power control in multi-user cognitive broadcast systems

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Science china(Information Sciences) 2012年第6期55卷 1402-1414页

作者： WANG QunHuan 1,2,3,WANG HuiMing 1,2,3 & YIN QinYe 1,3 1 School of Electronic and Information Engineering,xi'an Jiaotong university,xi'an 710049,china 2 state key Lab for integrated services networks,xidian university,xi'an 710071,china 3 Ministry of Education key Lab for Intelligent networks and network Security,xi'an Jiaotong university,xi'an 710071,china. 1. School of Electronic and Information Engineering Xi’an Jiaotong University Xi’an 710049 China2. State Key Lab for Integrated Services Networks Xidian University Xi’an 710071 China3. Ministry of Education Key Lab for Intelligent Networks and Network Security Xi’an Jiaotong University Xi’an 710071 China

Cognitive radio systems should not only have the ability to sense and exploit "frequency spectrum holes",but also the ability to sense and utilize "spatial spectrum holes".In this paper,we consider the issue of maximizing the throughput of the cognitive systems by fully utilizing "spatial spectrum holes" brought in by multiple cognitive users,in the scenario where a pair of licensed users and a cognitive broadcast system share multiple spectrum *** exploiting the channel reciprocity under the premise that the licensed system adopts the time-division-duplexing (TDD) mode,we propose a more practical cognitive access scheme that can sense the interference at the licensed user caused by the cognitive transmitter,based on the existing feedback signals from the licensed user to the licensed base *** both interferences from the licensed base station to the cognitive receiver and from the cognitive transmitter to the licensed user into consideration,we investigate the optimal user scheduling and power allocation scheme that can maximize the ergodic sum rate of the cognitive *** show that scheduling the user whose channel gain to interference and noise ratio (CGINR) is the largest for each frequency band is *** also derive the dynamic power allocation scheme meeting the three practical constraints,i.e.,the transmitter's average transmission power constraint,the power amplifier's instantaneous transmission power constraint,and the interference power constraint at the licensed *** result shows that in different coherent time intervals and different frequency bands,the power allocation has a multi-level waterfilling *** analysis shows that the strategy scheduling user with the largest CGINR introduces significant performance improvement compared with the traditional strategy scheduling user with the largest channel gain to noise ratio (CGNR).We also illustrate the impact of power constraints and the number of users on system p

关键词： cognitive radio distributed spatial spectrum holes opportunistic scheduling power allocation

Approximating maximum likelihood performance reduced dimension VBLAST detection algorithm

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Science china(Information Sciences) 2010年第7期53卷 1439-1445页

作者： CHENG WenChi & ZHANG HaiLin state key Lab of ISN, xidian university, xi’an 710071, china 1. state key Lab of ISN Xidian University Xi’an 710071 China

SM (spatial multiplexing) can effectively increase the information rate in multiple input multiple output system. BLAST is the typical representation of SM, especially VBLAST, which has some simple de- tection algorithms such as ML, ZF-DFE and ML-DFE, etc. However, the existing algorithms cannot approach ML performance. This paper discusses the effect for detection performance by the correlation of channel ma- trix, proposes a new algorithm-HPML detection algorithm, which can approach ML performance with low complexity. In the new algorithm, we travel the first d layers, and use the DFE procedure for the remaining layers, then perform ML detection for all obtained signals. Simulation results show that HPML can approach ML performance when the traveling numbers are not less than half of the number of transmitting antennas, and the algorithm complexity is smaller than ML.

关键词： BLAST correlation of channel matrix ML detecting algorithm HPML detecting algorithm

Asynchronous cooperative communication systems:A survey on signal designs

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Science china(Information Sciences) 2011年第8期54卷 1547-1561页

作者： WANG HuiMing 1,2 & xiA xiangGen 3 1 School of Electronic and Information Engineering, xi’an Jiaotong university, xi’an 710049,china 2 state key laboratory of integrated services networks, xidian university,xi’an 710049, china 3 Department of Electrical and Computer Engineering,university of Delaware,Newark,DE 19716,USA 1. School of Electronic and Information Engineering Xi’an Jiaotong University Xi’an 710049 China2. State Key Laboratory of Integrated Services Networks Xidian University Xi’an 710049 China3. Department of Electrical and Computer Engineering University of Delaware Newark DE 19716 USA

Cooperative communications is a promising technique for future high speed wireless *** systems may be formulated as virtual multi-input multi-output (MIMO) systems where spatial/cooperetive diversity is a key advantage. However,different from MIMO systems,one of the major chal- lenges for cooperative communications systems is that the cooperative transmissions in cooperative systems may be neither time nor frequency synchronized,since the transmissions are from multiple cooperative nodes at different *** existing signal designs for co-located MIMO systems may not be able to collect the cooperative diversity in cooperative communications *** paper gives an overview of recent research efforts on combating the time and frequency asynchronism of the cooperative communication *** focus on the signal designs (or space-time codings/modulations) to achieve full cooperative diversity,and summarize some of the resent distributed space-timing coding and space-frequency coding techniques to combat timing errors and frequency offsets,and in the meantime to achieve full cooperative diversity,in both one-way and two-way cooperative networks.

关键词： cooperative communications time and frequency offsets space-time coding space-frequency codes full cooperative diversity linear receiver

Price-based interference avoidance game in the Gaussian interference channel

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Science china(Information Sciences) 2012年第2期55卷 301-311页

作者： JING ZhenHai1,BAI BaoMing1 & MA xiao2 1state key laboratory of integrated services networks,xidian university,xi'an 710071,china 2Department of Electronics and Communication Engineering,Sun Yat-sen university,Guangzhou 510275,china 1. state key laboratory of integrated services networks Xidian University Xi’an 710071 China2. Department of Electronics and Communication Engineering Sun Yat-sen University Guangzhou 510275 China

This paper considers a distributed interference avoidance problem employing frequency assignment in the Gaussian interference channel(IC).We divide the common channel into several sub-channels and each user chooses one sub-channel for transmission in such a way that the total interference in the IC is *** mechanism named interference avoidance in this paper can be modeled as a competitive game *** a completely autonomous distributed iterative algorithm called distributed interference avoidance algorithm(DIA)is adopted to achieve the Nash equilibrium(NE)of the *** to the self-optimum,the DIA is a sub-optimal ***,through introducing an optimal compensation(or price)into the competitive game model,we successfully develop a compensation-based game model to approximate the optimal interference avoidance ***,an optimal algorithm called iterative optimal interference avoidance algorithm(IOIA)is proposed to reach the optimality of the interference avoidance *** analyze the implementation complexity of the proposed algorithm which is only O(N),with N standing for the number of users in the *** also give the proof on the convergence of the proposed *** performance upper bound and lower bound are derived for the IOIA *** simulation results show that the IOIA does reach the optimality under the condition of interference avoidance mechanism.

关键词： interference channel interference avoidance game theory

A NEW EFFICIENT ID-BASED PROXY BLIND SIGNATURE SCHEME

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Journal of Electronics(china) 2008年第2期25卷 226-231页

作者： Ming Yang Wang Yumin state key Lab of integrated Service network Xidian University Xi＇an 710071 China

In a proxy blind signature scheme,the proxy signer is allowed to generate a blind signature on behalf of the original signer. The proxy blind signature scheme is useful in several applications such as e-voting,e-payment,etc. Recently,Zheng,et al. presented an IDentity(ID) -based proxy blind sig-nature. In this paper,a new efficient ID-based proxy blind signature scheme from bilinear pairings is proposed,which can satisfy the security properties of both the proxy signatures and the blind signature schemes. Analysis of the scheme efficiency shows that the new scheme is more efficient than Zheng,et al.'s scheme. The proposed scheme is more practical in the real world.

关键词： Blind signature Proxy signature Bilinear pairing

Fair Non-Repudiation for Web services Transactions

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Wuhan university Journal of Natural Sciences 2010年第5期15卷 385-392页

作者： SU Ruidan,FU Shaofeng,ZHOU Lihua key laboratory of Computer network and Information Security of the Ministry of Education,xidian university,xi’an 710071,Shaanxi,china key laboratory of Computer network and Information Security of the Ministry of Education Xidian University Xi’an Shaanxi China

To safeguard the interests of transacting parties,non-repudiation mechanisms need to assure fairness and *** non-repudiation service currently implemented usually does not consider the requirement of fairness and the fair non-repudiation protocols to date can not be suitably applied in real environment due to its complex *** paper discusses the transaction-oriented non-repudiation requirement for Web services transaction,analyzes the constraints of the traditional model for the available fair non-repudiation protocols and designs a new Online-TTP fair non-repudiation *** new protocol provides a fair non-repudiation solution to secure Web services transactions and can be embedded into a single Web service *** protocol adopts evidence chained to decreasing the overhead of evidence verification and management and alleviates the overhead of certificate revocation checking and time-stamp generation for *** protocol has strong fairness,timeliness,efficiency and practicability.

关键词： fair non-repudiation Web services transaction evidence chaining timeliness

Multiary turbo code fitting for unitary space-time modulation and its MAP decoding algorithm

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Science china(Information Sciences) 2010年第12期53卷 2610-2619页

作者： ZHANG DaPeng 1,2,3,LU Ju 1,XU HongJi 1 & ZHANG xingYu 1 1 School of Information Science and Engineering,Shandong university,Jinan 250100,china 2 state key laboratory of integrated services networks,xidian university,xi'an 710077,china 3 Department of Avionics Engineering,First Aeronautical College of the Air Force,xinyang 464000,china 1. School of Information Science and Engineering Shandong University Jinan 250100 China2. State Key Laboratory of Integrated Services Networks Xidian University Xi’an 710077 China3. Department of Avionics Engineering First Aeronautical College of the Air Force Xinyang 464000 China

Unitary space-time modulation(USTM) fits for rapid Rayleigh flat fading channels as it can realize wireless communication when neither the transmitter nor the receiver knows the channel state information(CSI).However,an intrinsic problem is that only when the signal-to-noise ratio(SNR) is high can it give an ideal bit error rate(BER) *** existing bit-wise processing scheme of the combination of turbo code and USTM improves the BER performance and results in an unacceptable calculation complexity,storage and time delay *** this paper,we propose a multiary processing scheme and its corresponding multiary MAP decoding *** results verify that our scheme can reduce the system complexity while keep a good BER ***,we present the first analysis of the reason for the BER performance deterioration of the combination scheme at low SNR with the help of the definition of USTM.

关键词： multiple-input multiple-output unitary space-time modulation turbo code MAP decoding diversity

SAR image despeckling based on edge detection and nonsubsampled second generation bandelets

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Journal of Systems Engineering and Electronics 2009年第3期20卷 519-526页

作者： Zhang Wenge~(1,2),Liu Fang~(1,2),Jiao Licheng~(2,3)& Gao xinbo~(2,3) 1.School of Computer Science and Technology,xidian Univ.,xi’an 710071,P.R.china 2.key Lab.of Intelligent Perception and Image Understanding of Ministry of Education of china,xi’an 710071,P.R.china 3.Inst,of Intelligent Information Processing,xidian Univ.,xi’an 710071,P.R.china School of Computer Science and Technology Xidian Univ. Xi'an 710071 P. R. China key Lab. of Intelligent Perception and Image Understanding of Ministry of Education of china Xi'an 710071 P. R. China key Lab. of Intelligent Perception and Image Understanding of Ministry of Education of china Xi'an 710071 P. R. China Inst. of Intelligent Information Processing Xidian Univ. Xi'an 710071 P. R. China

To preserve the sharp features and details of the synthetic aperture radar （SAR） image effectively when despeckling, a despeckling algorithm with edge detection in nonsubsampled second generation bandelet transform （NSBT） domain is proposed. First, the Canny operator is utilized to detect and remove edges from the SAR image. Then the NSBT which has an optimal approximation to the edges of images and a hard thresholding rule are used to approximate the details while despeckling the edge-removed image. Finally, the removed edges are added to the reconstructed image. As the edges axe detected and protected, and the NSBT is used, the proposed algorithm reaches the state-of-the-art effect which realizes both despeckling and preserving edges and details simultaneously. Experimental results show that both the subjective visual effect and the mainly objective performance indexes of the proposed algorithm outperform that of both Bayesian wavelet shrinkage with edge detection and Bayesian least square-Gaussian scale mixture （BLS-GSM）.

关键词： computer image processing synthetic aperture radar speckle edge detection nonsubsampled second generation bandelet transform Canny operator threshold shrinkage.

Spectrum Resource Management of Cognitive Radio

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ZTE Communications 2009年第2期7卷 27-31页

作者： Liu Qin (state key laboratory of integrated services networks , xidian university, xi’an 710071 , P . R . china )

As the most important technology of CR, the wireless spectrum resource management technology is the key to CR performance improvement. By introducing the concept of resource space to describe wireless spectrum resource management in the field of CR technology, a data system of wireless resource management is formed that covers wireless spectrum resource space, resource grid and available resource atlas. Besides, the corresponding lamination distributional management structure and the resource management database are constructed. The resources description system and the management structure will become the theoretical concept foundation and reference of the CR spectrum resources management technology.

关键词： As Spectrum Resource Management of Cognitive Radio IEEE Figure