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Discovering and Maintaining Semantic Mappings between XML Schemas and Ontologies
Yuan An,Alex Borgida,John Mylopoulos 한국정보과학회 2008 Journal of Computing Science and Engineering Vol.2 No.1
There is general agreement that the problem of data semantics has to be addressed for XML data to become machine-processable. This problem can be tackled by defining a semantic mapping between an XML schema and an ontology. Unfortunately, creating such mappings is a tedious, time-consuming, and error-prone task. To alleviate this problem, we present a solution that heuristically discovers semantic mappings between XML schemas and ontologies. The solution takes as input an initial set of simple correspondences between element attributes in an XML schema and class attributes in an ontology, and then generates a set of mapping formulas. Once such a mapping is created, it is important and necessary to maintain the consistency of the mapping when the associated XML schema and ontology evolve. In this paper, we first offer a mapping formalism to represent semantic mappings. Second, we present our heuristic mapping discovery algorithm. Third, we show through an empirical study that considerable effort can be saved when discovering complex mappings by using our prototype tool. Finally, we propose a mapping maintenance plan dealing with schema evolution. Our study provides a set of effective solutions for building sustainable semantic integration systems for XML data.
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( Haobo Qing ),( Yuanan Liu ),( Gang Xie ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.5
Energy detection is a widely used method for spectrum sensing in cognitive radios due to its simplicity and accuracy. However, it is severely affected by the noise uncertainty. To solve this problem, a blind multiband spectrum sensing scheme which is robust to noise uncertainty is proposed in this paper. The proposed scheme performs spectrum sensing over the total frequency channels simultaneously rather than a single channel each time. To improve the detection performance, the proposal jointly utilizes the likelihood function combined with Gerschgorin radii of unitary transformed covariance matrix. Unlike the conventional sensing methods, our scheme does not need any prior knowledge of noise power or PU signals, and thus is suitable for blind spectrum sensing. In addition, no subjective decision threshold setting is required in our scheme, making it robust to noise uncertainty. Finally, numerical results based on the probability of detection and false alarm versus SNR or the number of samples are presented to validate the performance of the proposed scheme.
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Analysis of Joint Transmit and Receive Antenna Selection in CPM MIMO Systems
( Guowei Lei ),( Yuanan Liu ),( Xuefang Xiao ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3
In wireless communications, antenna selection (AS) is a widely used method for reducing comparable cost of multiple RF chains in MIMO systems. As is well known, most of literatures on combining AS with MIMO techniques concern linear modulations such as phase shift keying (PSK) and quadrature amplitude modulation (QAM). The combination of CPM and MIMO has been considered an optimal choice that can improve its capacity without loss of power and spectrum efficiency. The aim of this paper is to investigate joint transmit and receive antenna selection (JTRAS) in CPM MIMO systems. Specifically, modified incremental and decremental JTRAS algorithms are proposed to adapt to arbitrary number of selected transmit or receive antennas. The computational complexity of several JTRAS algorithms is analyzed from the perspective of channel capacity. As a comparison, the performances of bit error rate (BER) and spectral efficiency are evaluated via simulations. Moreover, computational complexity of the JTRAS algorithms is simulated in the end. It is inferred from discussions that both incremental JTRAS and decremental JTRAS perform close to optimal JTRAS in BER and spectral efficiency. In the sense of practical scenarios, adaptive JTRAS can be employed to well tradeoff performance and computational complexity.
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Xiaomin Jin,Yuanan Liu,Wenhao Fan,Fan Wu,Hongguang Zhang 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.2
Nowadays, many network devices have more than one network interface. Meanwhile, many protocols have been proposed to utilize multiple paths simultaneously. MPTCP (Multipath TCP) is a transport layer protocol that transfers data by multiple paths simultaneously, which is designed to improve the throughput and increase robustness of end to end transmission. However, when we use MPTCP, we find that MPTCP can not improve the throughput but even reduce the throughput in some cases. In this paper, we study this issue. Firstly, we study the effects of path characteristics for throughput of MPTCP, and find that path characteristics especially those bad paths have a great impact on the performance of MPTCP. Secondly, we analyze the reasons why the bad path characteristics have a serious impact on throughput of MPTCP, and propose a path selection method based on throughput prediction model and available bandwidth to improve the throughput. Finally, we validate our path selection method by simulations, and the results show that our method can improve the throughput of MPTCP.
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Analysis of Antenna Selection in Two-way Relaying MIMO Systems with CPM Modulation
( Guowei Lei ),( Hailan Chen ),( Yuanan Liu ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.3
Up to now, many state-of-arts have been proposed for two-way relaying system with linear modulations. The performances of antenna selection (AS) at both transmit and relay nodes need to be investigated in some two-way relaying multiple-input multiple-output (TWRM) systems. In this paper, the goal is focused on the study of nonlinear modulations, i.e., continuous phase modulation (CPM) in TWRM systems. Firstly, the joint phase trellis are simplified by reversed Rimoldi processing so as to reduce the systems’ complexity. Then the performances of joint transmit and receive antenna selection (JTRAS) with CPM modulations in two-way relaying MIMO systems are analyzed. More exactly, the pair wise probability (PEP) is used to evaluate the error performance based on the CPM signal matrix, which is calculated in terms of Laurent expression. Since the channels subject to two terminal nodes share common antennas at relay node R in multiple-access scheme, we revise the JTRAS algorithm and compare it to existing algorithm via simulation. Finally, the error performances for various schemes of antenna selection are simulated and compared to the analysis in this paper.
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Precoder Distribution and Adaptive Codebook in Wideband Precoding
Hang Long,김경진,Wei Xiang,Jing Wang,Yuanan Liu,Wenbo Wang 한국전자통신연구원 2012 ETRI Journal Vol.34 No.5
Based on wideband precoding (WBP) in the multiple-input multiple-output orthogonal frequency division multiplexing system, an adaptive nonuniform codebook is presented in this paper. The relationship between the precoder distribution and spatial correlation is analyzed at first. A closed-form expression based on overlapped isosceles triangles is proposed as an approximation of the precoder distribution. Then, the adaptive codebook design is derived with the approximate distribution to minimize quantization errors. The capacity and bit error rate performance demonstrate that the adaptive codebook with WBP outperforms the conventional fixed uniform codebook.
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