• Title, Summary, Keyword: spectrum

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Reevaluation of Seismic Fragility Parameters of Nuclear Power Plant Components Considering Uniform Hazard Spectrum

  • Park, In-Kil;Choun, Young-Sun;Seo, Jeong-Moon;Yun, Kwan-Hee
    • Nuclear Engineering and Technology
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    • v.34 no.6
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    • pp.586-595
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    • 2002
  • The Seismic probabilistic risk assessment (SPRA) or seismic margin assessment (SMA) have been used for the seismic safety evaluation of nuclear power plant structures and equipments. For the SPRA or SMA, the reference response spectrum should be defined. The site-specific median spectrum has been generally used for the seismic fragility analysis of structures and equipments in a Korean nuclear power plant Since the site-specific spectrum has been developed based on the peak ground motion parameter, the site-specific response spectrum does not represent the same probability of exceedance over the entire frequency range of interest. The uniform hazard spectrum is more appropriate to be used in seismic probabilistic risk assessment than the site- specific spectrum. A method for modifying the seismic fragility parameters that are calculated based on the site-specific median spectrum is described. This simple method was developed to incorporate the effects of the uniform hazard spectrum. The seismic fragility parameters of typical NPP components are modified using the uniform hazard spectrum. The modification factor is used to modify the original fragility parameters. An example uniform hazard spectrum is developed using the available seismic hazard data for the Korean nuclear power plant (NPP) site. This uniform hazard spectrum is used for the modification of fragility parameters.

A Generalized Markovian Based Framework for Dynamic Spectrum Access in Cognitive Radios

  • Muthumeenakshi, K.;Radha, S.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.5
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    • pp.1532-1553
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    • 2014
  • Radio spectrum is a precious resource and characterized by fixed allocation policy. However, a large portion of the allocated radio spectrum is underutilized. Conversely, the rapid development of ubiquitous wireless technologies increases the demand for radio spectrum. Cognitive Radio (CR) methodologies have been introduced as a promising approach in detecting the white spaces, allowing the unlicensed users to use the licensed spectrum thus realizing Dynamic Spectrum Access (DSA) in an effective manner. This paper proposes a generalized framework for DSA between the licensed (primary) and unlicensed (secondary) users based on Continuous Time Markov Chain (CTMC) model. We present a spectrum access scheme in the presence of sensing errors based on CTMC which aims to attain optimum spectrum access probabilities for the secondary users. The primary user occupancy is identified by spectrum sensing algorithms and the sensing errors are captured in the form of false alarm and mis-detection. Simulation results show the effectiveness of the proposed spectrum access scheme in terms of the throughput attained by the secondary users, throughput optimization using optimum access probabilities, probability of interference with increasing number of secondary users. The efficacy of the algorithm is analyzed for both imperfect spectrum sensing and perfect spectrum sensing.

Latest 5G Spectrum Auction in Germany (독일 5G주파수 최근(2019) 경매사례 분석)

  • Kim, H.J.;Lee, S.J.
    • Electronics and Telecommunications Trends
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    • v.34 no.6
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    • pp.17-27
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    • 2019
  • This paper introduces the 5G spectrum auction in Germany that occurred last summer and ended overheatedly after an extraordinarily long period. We describe the context of the latest German spectrum auction and trace the participants' bidding behavior. This case details the trend of the 5G spectrum auction and the factors that affect the spectrum auction as follows: First, it is determined that investment obligations that force network installations can be a financial burden to mobile network operators (MNOs) and require a careful approach. Second, excess demands can cause auction overheating and the spectrum supply volume needs to be determined by a proper demand forecast and investment incentive. Third, 'Set-Aside' for local usage aids in developing the vertical industry; however it limits the spectrum supply for mobiles and leads to higher bidding prices. Fourth, a modified adoption of a typical spectrum auction can alleviate MNO's financial burdens to secure the broadband spectrum. Finally, competition to secure the necessary bandwidth in the situation of limited spectrum supply may delay the process of the spectrum auction, causing it overheated.

Predicting required licensed spectrum for the future considering big data growth

  • Shayea, Ibraheem;Rahman, Tharek Abd.;Azmi, Marwan Hadri;Han, Chua Tien;Arsad, Arsany
    • ETRI Journal
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    • v.41 no.2
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    • pp.224-234
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    • 2019
  • This paper proposes a new spectrum forecasting (SF) model to estimate the spectrum demands for future mobile broadband (MBB) services. The model requires five main input metrics, that is, the current available spectrum, site number growth, mobile data traffic growth, average network utilization, and spectrum efficiency growth. Using the proposed SF model, the future MBB spectrum demand for Malaysia in 2020 is forecasted based on the input market data of four major mobile telecommunication operators represented by A-D, which account for approximately 95% of the local mobile market share. Statistical data to generate the five input metrics were obtained from prominent agencies, such as the Malaysian Communications and Multimedia Commission, OpenSignal, Analysys Mason, GSMA, and Huawei. Our forecasting results indicate that by 2020, Malaysia would require approximately 307 MHz of additional spectrum to fulfill the enormous increase in mobile broadband data demands.

Spectrum Sensing Technologies for Cognitive Radio Based Interactive Broadcasting Services

  • Lim Kyu-Tae;Hur Young-Sik;Lee Jeong-Suk;Kim Ki-Hong;Lee Chang-Ho;Kim Hak-Sun;Laskar Joy
    • Broadcasting and Media Magazine
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    • v.11 no.1
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    • pp.68-77
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    • 2006
  • The Cognitive Radio (CR) technology is a promising solution for exploiting the limited spectrum resources and providing flexibility of spectrum usage. Future interactive broadcasting service can be realized by utilizing CR concept, since the up-link return channel can be found by the spectrum sensing method, which is core functional block of the CR system. In this paper, the spectrum sensing technologies of CR system is presented. First the system architecture of the CR with spectrum sensing block is presented. The suggested spectrum sensing technique consists of the coarse and the fine spectrum sensing. The coarse spectrum sensing technique adopted the wavelet transform to provide the multi-resolution sensing feature - Multi-Resolution Spectrum Sensing (MRSS). The fine spectrum sensing technique uses the beneficial properties of the autocorrelation function Analog Auto-Correlation (AAC). The simulation results for the proposed sensing technologies are presented for various incumbent signals.

Finding Alternative Solutions and Analyzing Spectrum Policy Cost on Spectrum Usage (전파사용 기반의 전파정책성 비용제도 분석 및 대안의 결정)

  • Ahn, Choon-Soo;Lee, Dong-Hyung;Youm, Se-Kyoung
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.35 no.2
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    • pp.181-188
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    • 2012
  • The fee system on spectrum usage is a usage fee that is charged for using spectrum provided by a wireless tower, and is used for management and promotion of the waves. The current fee system for spectrum usage in South Korea has faced many problems, such as complex calculation for fees, unjustified charges, unfairness in cost sharing among providers, and general inefficiency of operation. This study focuses on comparison of fee systems for spectrum usage of South Korea and other foreign countries, extraction of the root causes and problems by case analyses, and recommendation for better solutions to make a reasonable fee system for spectrum usage. The result of this study can be used as a solution to render spectrum usage more effective.

A Survey on Spectrum Sharing in Cognitive Radio Networks

  • Xu, Tangwen;Li, Zhenshuang;Ge, Jianhua;Ding, Haiyang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.11
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    • pp.3751-3774
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    • 2014
  • With the rapid development of wireless communication, the confliction between the scarce frequency resources and the low spectral efficiency caused by the stationary spectrum sharing strategies seriously restricts the evolution of the future mobile communication. For this purpose, cognitive radio (CR) emerges as one of the most promising inventions which can overcome the spectrum shortage. As the key technology and main objective of CR, spectrum sharing can make full use of the limited spectrum, alleviate the scarcity of frequency resources and improve the system utilities, playing thereby an important role in improving the system performance of cognitive radio networks (CRNs). In this survey, the spectrum sharing in CRNs is discussed in terms of the sharing process, mainstream sharing technologies and spectrum sharing models. In particular, comparisons of different spectrum sharing strategies are concluded, as well as that of different spectrum sensing schemes in sharing procedure. Moreover, some application examples of the spectrum sharing in CRNs, such as smart grid, public safety, cellular network and medical body area networks are also introduced. In addition, our previous related works are presented and the open research issues in the field of spectrum sharing are stated as well.

Comparative Analysis of Policies to Vitalize Spectrum Sharing Ecosystem using System Dynamics (시스템 다이내믹스를 이용한 주파수 공유 생태계 활성화 정책대안 비교 분석 연구)

  • Song, Hee Seok;Kim, Jae Kyung;Kim, Taehan
    • Journal of Information Technology Applications and Management
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    • v.21 no.4_spc
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    • pp.431-447
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    • 2014
  • Demand of spectrum resource is tremendously increasing and this trend will continue as more IT services such as cloud computing, smart devices, Internet of Things are provided through wireless network. Recent development of spectrum sharing technology has drawn attention to spectrum policy makers as a promising way to overcome the expected spectrum shortage problem. However, technology-based solution to spectrum shortage problem may not be sustainable since the solution affect only one aspect of spectrum sharing ecosystem. To understand the whole picture of spectrum shortage problem, policies to vitalize spectrum sharing ecosystem were proposed based on the analysis of System Dynamics causal map in the previous study. This study compares and analyzes the effect of those proposed vitalization policies by using System Dynamics simulation. Among seven alternative policies, combined application of demand acceleration policy and technology development policy was found to be more effective for better utilization of spectrum. The effect of demand acceleration policy was offset when other policies are applied together except supply acceleration policy which shows better spectrum sharing.

Efficient Method for Recovering Spectral Reflectance Using Spectrum Characteristic Matrix (스펙트럼 특성행렬을 이용한 효율적인 반사 스펙트럼 복원 방법)

  • Sim, Kyudong;Park, Jong-Il
    • Journal of Korea Multimedia Society
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    • v.18 no.12
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    • pp.1439-1444
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    • 2015
  • Measuring spectral reflectance can be regarded as obtaining inherent color parameters, and spectral reflectance has been used in image processing. Model-based spectrum recovering, one of the method for obtaining spectral reflectance, uses ordinary camera with multiple illuminations. Conventional model-based methods allow to recover spectral reflectance efficiently by using only a few parameters, however it requires some parameters such as power spectrum of illuminations and spectrum sensitivity of camera. In this paper, we propose an enhanced model-based spectrum recovering method without pre-measured parameters: power spectrum of illuminations and spectrum sensitivity of camera. Instead of measuring each parameters, spectral reflectance can be efficiently recovered by estimating and using the spectrum characteristic matrix which contains spectrum parameters: basis function, power spectrum of illumination, and spectrum sensitivity of camera. The spectrum characteristic matrix can be easily estimated using captured images from scenes with color checker under multiple illuminations. Additionally, we suggest fast recovering method preserving positive constraint of spectrum by nonnegative basis function of spectral reflectance. Results of our method showed accurately reconstructed spectral reflectance and fast constrained estimation with unmeasured camera and illumination. As our method could be conducted conveniently, measuring spectral reflectance is expected to be widely used.

Spectrum Sharing SDMA with Limited Feedback: Throughput Analysis

  • Jo, Han-Shin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.6 no.12
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    • pp.3237-3256
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    • 2012
  • In the context of effective usage of a scarce spectrum resource, emerging wireless communication standards will demand spectrum sharing with existing systems as well as multiple access with higher spectral efficiency. We mathematically analyze the sum throughput of a spectrum sharing space-division multiple access (SDMA) system, which forms a transmit null in the direction of other coexisting systems while satisfying orthogonal beamforming constraints. For a large number of users N, the SDMA throughput scales as log N at high signal-to-noise ratio (SNR) ((J-1) loglog N at normal SNR), where J is the number of transmit antennas. This indicates that multiplexing gain of the spectrum sharing SDMA is $\frac{J-1}{J}$ times less than that of the non-spectrum sharing SDMA only using orthogonal beamforming, whereas no loss in multiuser diversity gain. Although the spectrum sharing SDMA always has lower throughput compared to the non-spectrum sharing SDMA in the non-coexistence scenario, it offers an intriguing opportunity to reuse spectrum already allocated to other coexisting systems.