• Title, Summary, Keyword: FDD

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On the Feasibility of Dual Mode LTE-FDD/TDD and Dual Mode WiMAX-TDD/LTE-TDD (듀얼모드 LTE-FDD/TDD 및 듀얼모드 WiMAX-TDD/LTE-TDD에 대한 실현가능성 연구)

  • Cho, Bong-Youl;Kim, Jin-Young
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.5
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    • pp.45-55
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    • 2010
  • While Long Term Evolution-Frequency Division Duplexing (LTE-FDD) is regarded as one of the strong candidates for "4G" wireless broadband access in FDD field, LTE-Time Division Duplexing (TDD) is emerging as one possible migration path for WiMAX-TDD in some cases as well as the migration path for Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). In this paper, we analyze the feasibility of dual mode with LTE-TDD in two combinations: dual mode LTE-FDD/TDD and dual mode Worldwide Interoperability for Microwave Access (WiMAX)-TDD/LTE-TDD. Thanks to the commonality in numerology, terminology, and frame structure between LTE-FDD and LTE-TDD, dual mode LTE-FDD/TDD looks feasible in a cost-effective manner. Thanks to the commonality in scheduling algorithm, control mechanism, and supported spectrum bands, it is shown that dual mode WiMAX-TDD/LTE-TDD looks feasible as well. It should be also noted that the commonality in numerology and frame structure is critical for building a chip while the commonality in algorithms and control mechanisms is critical to make it work.

플로피 디스크 구동장치 (FDD)

  • 강인구;전중기
    • Journal of the KSME
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    • v.25 no.5
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    • pp.394-399
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    • 1985
  • 금성통신에서 특정연구 사업으로 추진해 온 독자모델인 GSF-480를 중심으로 일반적인 FD D의 특성과 메카니즘(mechanism)에 대하여 기술하고자 한다. 현재 FDD의 주류를 이루고 있는 것이 5v1/4인치 양면 FDD이지만 소형화 대용량화에 의하여 점차 새로운 제품 즉 3.5인치, 3인치 FDD, 5v1/4인치 1M, 1.6M 버전(version)등이 개발되었다. 뿐만 아니라 트랙밀도를 높이는 외 에도 선밀도를 증가시키는 수직기록 방식도 개발될 전망이다. 그러나 대용량화가 되기 위하여 서는 FDD 상호간의 호환의 문제를 어떻게 하든 줄여야 할 것이다. 이를 위해서는 전술한 바와 같이 악세스 메카니즘의 정밀도 및 클램프시의 오차등 오프트랙 요인이 되는 것을 잘 고려하여야 한다. 국내에서는 기술도입 또는 자체개발로 FDD를 생산하고 있으며 금성통신은 83년 정부의 특정 연구사업으로 FDD를 개발 생산하고 있다. 앞으로 소형컴퓨터의 시장이 확대되고 수출이 늘어나게 되면 FDD의 시장도 확대될 것으로 전망되며 따라서 제품개발도 더욱 활발해질 것으로 기대된다.

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Model-based and wavelet-based fault detection and diagnosis for biomedical and manufacturing applications: Leading Towards Better Quality of Life

  • Kao, Imin;Li, Xiaolin;Tsai, Chia-Hung Dylan
    • Smart Structures and Systems
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    • v.5 no.2
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    • pp.153-171
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    • 2009
  • In this paper, the analytical fault detection and diagnosis (FDD) is presented using model-based and signal-based methodology with wavelet analysis on signals obtained from sensors and sensor networks. In the model-based FDD, we present the modeling of contact interface found in soft materials, including the biomedical contacts. Fingerprint analysis and signal-based FDD are also presented with an experimental framework consisting of a mechanical pneumatic system typically found in manufacturing automation. This diagnosis system focuses on the signal-based approach which employs multi-resolution wavelet decomposition of various sensor signals such as pressure, flow rate, etc., to determine leak configuration. Pattern recognition technique and analytical vectorized maps are developed to diagnose an unknown leakage based on the established FDD information using the affine mapping. Experimental studies and analysis are presented to illustrate the FDD methodology. Both model-based and wavelet-based FDD applied in contact interface and manufacturing automation have implication towards better quality of life by applying theory and practice to understand how effective diagnosis can be made using intelligent FDD. As an illustration, a model-based contact surface technology an benefit the diabetes with the detection of abnormal contact patterns that may result in ulceration if not detected and treated in time, thus, improving the quality of life of the patients. Ultimately, effective diagnosis using FDD with wavelet analysis, whether it is employed in biomedical applications or manufacturing automation, can have impacts on improving our quality of life.

Analysis of Capacity Decrease Through Calculating Statistically the Amount of Interference From IMT-2000 TDD System to FDD System (IMT-2000 TDD시스템에서 FDD시스템으로의 통계적인 간섭량 계산을 통한 FDD 시스템의 용량 감소 분석)

  • Kim, Sung-Jin;Choi, Sang-Sung;Lee, Hyung-Soo
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • pp.572-575
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    • 2003
  • There is two System for IMT-2000 Service. one is FDD(Frequency Division Duplex), the other is TDD(Time Division Duplex) system. At the 1920MHz, they have common boundary in IMT-2000 frequency allocation of Korea. In this paper, The amount of Interference From TDD MS(Mobile Station) and BS(Base Station) to FDD BS is Analyzed for Investigation on capacity variation of FDD service by frequency separation. the result and methodology in this paper will be used basically for calculating the guard-band between FDD and TDD service in the future

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A Systematic Literature Review on Secure Software Development using Feature Driven Development (FDD) Agile Model (기능주도개발 Agile 방법을 사용할 때의 안전한 소프트웨어 개발에 관한 문헌연구)

  • Arbain, Adila Firdaus;Ghani, Imran;Jeong, Seung Ryul
    • Journal of Internet Computing and Services
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    • v.15 no.1
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    • pp.13-27
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    • 2014
  • Agile methodologies have gained recognition as efficient development processes through their quick delivery of software, even under time constraints. However, like other agile methods such as Scrum, Extreme Programming (XP) and The Dynamic Systems Development Method (DSDM), Feature Driven Development (FDD) has been criticized due to the unavailability of security elements in its twelve practices. In order to examine this matter more closely, we conducted a systematic literature review (SLR) and studied literature for the years 2001-2012. Our findings highlight that, in its current form, the FDD model partially supports the development of secure software. However, there is little research on this topic, as detailed information about the usage of secure software is rarely published. Thus, we have been able to conclude that the existing five phases of FDD have not been enough to develop secure software until recently. For this reason, security-based phase and practices in FDD need to be proposed.

On Mobility-Supporting Transmit Beamforming in MISO FDD Wireless Systems

  • Lee, Woo-Kwon;Sepko, Brian J.
    • Journal of Communications and Networks
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    • v.10 no.3
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    • pp.308-315
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    • 2008
  • When operating in frequency-division duplex (FDD) mode, transmit beamforming in multiple-input single-output (MISO) wireless communication systems typically requires accurate knowledge of downlink channel state information (CSI) at the transmitter. In practical FDD systems, obtaining such downlink CSI at the transmitter is challenging, if not impractical. To circumvent such challenge and support user mobility, we present a new method for transmit beamforming based on simple beam-control commands (BCCs) in MISO FDD mobile systems. We then numerically evaluate the effects of BCC errors in terms of transmit power efficiency, system capacity, and outage probability.

Trends of TDD/FDD LTE Network Convergence (TDD/FDD LTE 네트워크 컨버전스 동향)

  • Seol, S.H.;Kim, S.C.
    • Electronics and Telecommunications Trends
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    • v.30 no.3
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    • pp.123-130
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    • 2015
  • 본고는 TDD(Time Division Duplex)/FDD(Frequency-Division Duplex) 네트워크 컨버전스를 통해 LTE(Long Term Evolution) 서비스를 제공하고 있는 주요 사업자들의 동향에 대하여 분석 정리하였다. 본고의 분석 결과에 따르면, 상당수 사업자가 보유 주파수 여건을 고려하여 경쟁력을 높이기 위한 목적으로 네트워크 컨버전스를 추진한 것으로 나타났다. 향후 국내에서도 TDD/FDD 컨버전스를 촉진하고 주파수 이용 효율성을 개선하기 위한 정책방안에 대한 모색이 필요하다고 사료된다.

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Normalized CP-AFC with multistage tracking mode for WCDMA reverse link receiver (다단 추적 모드를 적용한 WCDMA 역방향 링크 수신기용 Normalized CP-AFC)

  • Do, Ju-Hyeon;Lee, Yeong-Yong;Kim, Yong-Seok;Choe, Hyeong-Jin
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.39 no.8
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    • pp.14-25
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    • 2002
  • In this paper, we propose a modified AFC algorithm which is suitable for the implementation of WCDMA reverse link receiver modem. To reduce the complexity, the modified CP-FDD algorithm named 'Normalized CP-FDD' is applied to the AFC loop. The proposed FDD algorithm overcomes the conventional CP-FDD's sensitivity to the variance of input signal amplitude and increases the linear range of S -curve. Therefore, offset frequency estimation using the proposed scheme can be more stable than the conventional method. Unlike IS-95, since pilot symbol in WCDMA is not transmitted continuously, we introduce a moving average filter at the FDD input to increase the number of cross-product. So, tracking speed and stability are improved. For more rapid frequency acquisition and tracking, we adopt a multi-stage tracking mode. Using NCO having ROM table structure, the frequency offset is compensated. We applied the proposed algorithm in the implementation of WCDMA base station modem successfully.

Fault Location Diagnosis Technique of Photovoltaic Power Systems through Statistic Signal Process of its Output Power Deviation (출력편차의 통계학적 신호처리를 통한 태양광 발전 시스템의 고장 위치 진단 기술)

  • Cho, Hyun Cheol
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.11
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    • pp.1545-1550
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    • 2014
  • Fault detection and diagnosis (FDD) of photovoltaic (PV) power systems is one of significant techniques for reducing economic loss due to abnormality occurred in PV modules. This paper presents a new FDD method against PV power systems by using statistical comparison. This comparative approach includes deviation signals between the outputs of two neighboring PV modules. We first define a binary hypothesis testing under such deviation and make use of a generalized likelihood ratio testing (GLRT) theory to derive its FDD algorithm. Additionally, a recursive computational mechanism for our proposed FDD algorithm is presented for improving a computational effectiveness in practice. We carry out a real-time experiment to test reliability of the proposed FDD algorithm by utilizing a lab based PV test-bed system.

Interference Resolving Radio Resource Allocation Scheme in a TDD-OFDMA/FDD-CDMA Hierarchical Over lay Cellular System

  • Lee, Yeonwoo;Kim, Kyung-Ho
    • Journal of Korea Multimedia Society
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    • v.16 no.7
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    • pp.862-869
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    • 2013
  • In order to support a cell-independent traffic asymmetry, the conventional TDD system cannot avoid crossed time slot (CTS) interference. Moreover, the TDD/FDD hierarchical overlay cellular systems is taken into account as a generally accepted cell model in a heterogeneous radio environment. In this paper, we propose an interference resolving radio resource allocation technique in a TDD-OFDMA cellular system that overlays a FDD-CDMA cell. In our proposed scheme, we exploit under-used FDD-CDMA uplink resource by TDD mobile abiding by a region based time slot(TS) allocation which in turn mitigates CTS interference considerably. It is demonstrated that combined with under-used resource utilization scheme based on mobile's location, the proposed technique can reduce CTS interference considerably and support the asymmetric traffic in TDD system.