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Security for cyberspace:challenges and opportunities

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Frontiers of Information Technology & Electronic engineering 2018年第12期19卷 1459-1461页

作者： Jiang-xing WU Jian-hua LI Xin-sheng JI national digital switching system engineering & technological r&d center School of Cyber Security Shanghai Jiao Tong University

Nowadays,cyberspace has become the "fifth frontier"after the ocean,land,air,and *** the globalization of information,cyberspace has never faced so many challenges,such as principle innovation,theory innovation,technology innovation,and application ***,the transition from traditional cyberspace to new cyberspace is inevitable. In the future,cyberspace will have many important characteristics,such as openness,heterogeneity,mobility,dynamism,and security.

关键词： Security for cyberspace Sea land air space

Optimization-based image reconstruction in x-ray computed tomography by sparsity exploitation of local continuity and nonlocal spatial self-similarity

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Chinese Physics B 2016年第7期25卷 557-565页

作者：张瀚铭王林元李磊闫镔蔡爱龙胡国恩 national digital switching system engineering and technological research center Zhengzhou 450002 China

The additional sparse prior of images has been the subject of much research in problems of sparse-view computed tomography（CT） reconstruction. A method employing the image gradient sparsity is often used to reduce the sampling rate and is shown to remove the unwanted artifacts while preserve sharp edges, but may cause blocky or patchy *** eliminate this drawback, we propose a novel sparsity exploitation-based model for CT image reconstruction. In the presented model, the sparse representation and sparsity exploitation of both gradient and nonlocal gradient are *** new model is shown to offer the potential for better results by introducing a similarity prior information of the image structure. Then, an effective alternating direction minimization algorithm is developed to optimize the objective function with a robust convergence result. Qualitative and quantitative evaluations have been carried out both on the simulation and real data in terms of accuracy and resolution properties. The results indicate that the proposed method can be applied for achieving better image-quality potential with the theoretically expected detailed feature preservation.

关键词： computed tomography image reconstruction sparsity exploitation nonlocal gradient

Novel Fourier-based iterative reconstruction for sparse fan projection using alternating direction total variation minimization

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Chinese Physics B 2016年第3期25卷 458-465页

作者：金朝张瀚铭闫镔李磊王林元蔡爱龙 national digital switching system engineering and technological research center Zhengzhou 450002 China

Sparse-view x-ray computed tomography （CT） imaging is an interesting topic in CT field and can efficiently decrease radiation dose. Compared with spatial reconstruction, a Fourier-based algorithm has advantages in reconstruction speed and memory usage. A novel Fourier-based iterative reconstruction technique that utilizes non-uniform fast Fourier transform （NUFFF） is presented in this work along with advanced total variation （TV） regularization for a fan sparse-view CT. The proposition of a selective matrix contributes to improve reconstruction quality. The new method employs the NUFFT and its adjoin to iterate back and forth between the Fourier and image space. The performance of the proposed algorithm is demonstrated through a series of digital simulations and experimental phantom studies. results of the proposed algorithm are compared with those of existing TV-regularized techniques based on compressed sensing method, as well as basic algebraic reconstruction technique. Compared with the existing TV-regularized techniques, the proposed Fourier-based technique significantly improves convergence rate and reduces memory allocation, respectively.

关键词： Fan iterative reconstruction Fourier-based iterative reconstruction technique alternating directionmethod non-uniform fast Fourier transform

The dFF-PSP Iterative Separation and Theoretical Bound for PCMA with Long Memory

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Chinese Journal of Electronics 2016年第5期25卷 880-885页

作者： CUI Penghui JIANG Hua CAO Kai LI Taozhu national digital switching engineering technological research center

This paper proposes the decision feedbackfeedforward per-survivor processing(dFF-PSP) iterative separation algorithm and the Monte Carlo integrationbased method to compute the theoretical bound for Paired carrier multiple access(PCMA) Single channel blind separation(SCBS) which is highly complex with long memory. The truncated PSP is employed while the pre- and post- cursors are disregarded to control the *** delayed decisions feedforward and local decisions feedback filters are designed to process the pre- and postcursors. The Bit-interleaved code modulation iterative decoder(BICM-Id) is combined with the second soft decision of the truncated PSP to obtain a better *** mixture signal model is regarded as a Multiple-access channel(MAC) with memory, and the theoretical performance bound is obtained via entropy inequality, Monte Carlo integration and Fano inequality. Simulation results show that the dFF-PSP iterative separation provides the good tradeoff between complexity and performance.

关键词： Paired carrier multiple access(PCMA) Single channel blind separation(SCBS) decision feedbackfeedforward Per-survivor processing Bit-interleaved code modulation iterative decoder(BICM-Id) Multiple-access channel(MAC) Theoretical performance bound

Achieving fair service with a hybrid scheduling scheme for CICQ switches

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Science China(Information Sciences) 2012年第3期55卷 689-700页

作者： HU HongChao , GUO YunFei, YI Peng & LAN JuLong department of Broadband Information Networks, national digital switching system engineering & technological r&d center (NdSC), Zhengzhou 450002, China department of Broadband Information Networks National Digital Switching System Engineering & Technological R&D Center (NDSC) Zhengzhou China

Providing performance guarantees for arriving traffic flows has become an important measure for today’s routing and switching systems. However, none of current scheduling algorithms built on CICQ (combined input and cross-point buffered) switches can provide flow level performance guarantees. Aiming at meeting this requirement, the feasibility of implementing flow level scheduling is discussed thoroughly. Then, based on the discussion, it comes up with a hybrid and stratified fair scheduling (HSFS) scheme, which is hierarchical and hybrid, for CICQ switches. With HSFS, each input port and output port can schedule variable length packets independently with a complexity of O(1). Theoretical analysis show that HSFS can provide delay bound, service rate and fair performance guarantees without speedup. Finally, we implement HSFS in SPES (switch performance evaluation system) to verify the analytical results.

关键词： switching fabric scheduling policy load balancing dynamical re-routing

Providing personalized converged services based on flexible network reconfiguration

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Science China(Information Sciences) 2011年第2期54卷 334-347页

作者： HU YuXiang, LAN JuLong & WU JiangXing national digital switching system engineering and technological research center, Zhengzhou 450002, China national digital switching system engineering and technological research center Zhengzhou China

recent developments show a progressing convergence of networks, services, and applications, which results in the necessity for new approaches to provide a ubiquitous experience on converged networks for specialized hi... 详细信息

ract>recent developments show a progressing convergence of networks, services, and applications, which results in the necessity for new approaches to provide a ubiquitous experience on converged networks for specialized high data-rate services. A fundamental diversifying attribute for the future physical network convergence paradigm is pressing. In this paper, we make researches on converged resource reconfiguration model of substrate physical network based on hardware virtualization and provide a service oriented network architecture as a network convergence primitive. Based on the idea of hardware virtualization which is performed by platform deformation and component processing with reconfiguration (here, they are realized as reconfigurable routers (rr)), the substrate converged network, which inter-connects various access networks by reconfigurable routers, could be mapped into multiplex service oriented logical networks, supports dynamic reconfiguration due to diversified quality of services under heterogeneous environment, and therefore provides more flexible and high- speed multiple services. In addition, to demonstrate the generality of our model, we provide a prototype of reconfigurable router. The design, implementation and task scheduling as well as both hardware and software reconfiguration process of reconfigurable router are discussed in detail. Our evaluation shows that reconfigurable router is transparent for upper service-providing networks and results in little performance impact on the service delivery when both hardware and software reconfiguration are used.

关键词： network convergence hardware virtualization resource reconfiguration reconfigurable router

Achieve load balancing with a dynamic re-routing CICQ switching scheme

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Science China(Information Sciences) 2012年第2期55卷 407-418页

作者： HU HongChao,GUO YunFei,YI Peng & LAN JuLong department of Broadband Information Networks,national digital switching system engineering & technological r&d center(NdSC),Zhengzhou 450002,China department of Broadband Information Networks National Digital Switching System Engineering & Technological R&D Center (NDSC) Zhengzhou China

Multi-path based routing and switching can achieve network-wide load balancing and reduce the port conflicts of switching *** by this novel idea,in this paper,through analyzing the feasibility of implementing multi-next-hops in core switching networks comprehensively,we advance a switching scheme called MHrS(multi-next-hop re-routing switch)and a forwarding table management scheme called HMFT(hierarchical multi-stage forwarding table)to support multi-next-hop dynamical *** implements dynamical re-routing in the switches according its congestion status to achieve real-time load balancing,while HMFT can provide traffic with different forwarding paths based on their QoS *** analysis and simulation results show that switches equipped with HMFT and MHrS can provide good delay and throughput ***,they can reduce port conflicts significantly.

关键词： switching fabric scheduling policy load balancing dynamical re-routing

Using the Cooperative Game for Service Placement of Virtual Network Functions

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China Communications 2016年第S1期13卷 146-157页

作者： XIONG Gang HU Yuxiang WANG Weiming WANG Lingqiang national digital switching system engineering and technological r&d center School of Information and Electronic engineering Zhejiang Gongshang University Zhongxing Telecommunication Equipment Corporation

To address the issues that middleboxes as a fundamental part of today's networks are facing, Network Function Virtualization(NFV)has been recently proposed, which in essence asserts to migrate hardware-based middleboxes into software-based virtualized function *** to the demands of virtual services placement in NFV network environment, this paper models the service amount placement problem involving with the resources allocation as a cooperative game and proposes the placement policy by Nash Bargaining Solution(NBS). Specifically,we first introduce the system overview and apply the rigorous cooperative game-theoretic guide to build the mathematical model, which can give consideration to both the responding efficiency of service requirements and the allocation *** a distributed algorithm corresponding to NBS is designed to achieve predictable network performance for virtual instances ***, with simulations under various scenarios,the results show that our placement approach can achieve high utilization of network through the analysis of evaluation metrics namely the satisfaction degree and fairness index. With the suitable demand amount of services, the average values of two metrics can reach above 90%. And by tuning the base placement, our solution can enable operators to flexibly balance the tradeoff between satisfaction and fairness of resourcessharing in service platforms.

关键词： Middlebox game theory network function virtualization software defined networking

direction finding for two-dimensional incoherently distributed sources with Hadamard shift invariance in non-uniform orthogonal arrays

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Chinese Journal of Aeronautics 2018年第12期31卷 2260-2269页

作者： Zhengliang dAI Weijia CUI daming WANG Bin BA Chao WANG Yankui ZHANG national digital switching system engineering&technological research center Zhengzhou 450001China

This paper proposes a novel algorithm for Two-dimensional(2d) central directionof-Arrival(dOA) estimation of incoherently distributed sources. In particular, an orthogonal array structure consisting of two Non-uniform Linear Arrays(NLAs) is considered. Based on first-order Taylor series approximation, the Generalized Array Manifold(GAM) model can first be established to separate the central dOAs from the original array manifold. Then, the Hadamard rotational invariance relationships inside the GAMs of two NLAs are identified. With the aid of such relationships, the central elevation and azimuth dOAs can be estimated through a search-free polynomial rooting method. Additionally, a simple parameter pairing of the estimated 2d angular parameters is also accomplished via the Hadamard rotational invariance relationship inside the GAM of the whole array. A secondary but important result is a derivation of closed-form expressions of the Cramer-rao lower bound. The simulation results show that the proposed algorithm can achieve a remarkably higher precision at less complexity increment compared with the existing low-complexity methods, which benefits from the larger array aperture of the NLAs. Moreover, it requires no priori information about the angular distributed function.

关键词： Array signal processing Cramer-rao lower bound direction-of-Arrival(dOA) estimation Hadamard rotational invariance Incoherently distributed sources Non-uniform orthogonal array