• Title/Summary/Keyword: hybrid acquisition

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RETRACTED: Double-Dwell Hybrid Acquisition in a DS-UWB System

  • Wang, Yupeng;Chang, Kyung-Hi
    • ETRI Journal
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    • v.29 no.1
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    • pp.1-7
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    • 2007
  • In this paper, we analyze the performance of double-dwell hybrid initial acquisition in a direct sequence ultra-wideband (DS-UWB) system via detection, miss, false alarm probabilities, and mean acquisition time. In the analysis, we consider the effect of the acquisition sequence as well as the deployment scenario of the abundant multipath components over small coverage of the piconet in the DS-UWB system. Based on the simulation, we obtain various performance measures for the mean acquisition time by varying parameters such as the total number of hypotheses to be searched, subgroup size, and dwell time. We thereupon suggest the optimum parameter set for the initial acquisition in the DS-UWB system.

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A Study on The Hybrid Acquisition Performance of MC DS-CDMA Over Multipath Fading Channel (다중경로 환경에서 MC DS-CDMA시스템의 직.병렬 혼합 동기 획득에 관한 연구)

  • Kim, Won-Sbu;Kim, Kyung-Won;Park, Jin-Soo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.10
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    • pp.1968-1976
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    • 2007
  • This paper proposes a hybrid pseudo-noise (PN) code acquisition scheme for Multicarrier Direct Sequence - Code Division Multiple Access (MC DS-CDMA) mobile communication systems on the code acquisition performance for Nakagami-m fading channel. The hybrid acquisition scheme combines parallel search with serial search to cover the whole uncertainty region of the input code phase. It has a much simpler acquisition hardware structure than the total parallel acquisition and can achieve the mean acquisition time (MAT) slightly inferior to that of the total parallel acquisition. The closed-form expressions of the detection and false-alarm probabilities are derived.

Improvement of code acquisition time in DS/SS systems using a hybrid scheme (복합방식을 이용한 직접대역확산통신시스템의 코드획득 성능개선)

  • 조권도;김선영
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.3
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    • pp.684-691
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    • 1996
  • Since the period of a spreading code in DS/SS communication systems is generally long, it is necessary to make the code acquisition as fast as possible. The code acquisition time can be sued as a measure to evaluate the performance of code acquisition systems. The search rate of serial search codee acquisition system used in the coventional CDMA cellular system is lower than that of the matched filter technique. In order to reduce the code acquisition time, this paper proposes hybrid code acquisition system composed filters combined with serial search blocks. In the proposed system, the matched filter sweeps possible code phases fast and the acquired phase information is verified by the serial search block. The mean and the variance of its acquisition time are calculated and compared with those of double dwell serial search system. The results indicate better performance of the proposed system by yielding its small vaues of the mean and the variance of code acquisition time.

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Double-Dwell Hybrid Acquisition in DS-UWB System

  • Wang YuPeng;Chang Kyung-Hi
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.7A
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    • pp.696-701
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    • 2006
  • In this paper, we analyze the performance of double-dwell hybrid initial acquisition in DS-UWB system via detection, miss, false alarm probabilities and mean acquisition time. In the analysis, we consider the effect of the acquisition sequence, and deployment scenario of the abundant multipath components over the small coverage of the piconet in DS-UWB system. Based on the simulation, we obtain various performance on the mean acquisition time by varying the parameters, such as the total number of hypotheses to be searched, subgroup size, and dwell time. Then, we suggest the optimum parameter set for the initial acquisition in DS-UWB system.

Hybrid PN Code Search with Soft-decision Technique (연판정 하이브리드 PN 코드 동기 획득 기법)

  • Lee Seong-Joo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.7A
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    • pp.682-688
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    • 2006
  • In this paper, a soft-decision method for initial PN code acquisition in pilot-channel aided Direct Sequence Code Division Multiple Access (DS-CDMA) systems is proposed in order to improve the acquisition performance. We apply this technique to the conventional hybrid search algorithm and analyze it in terms of mean code acquisition time. For the analysis, we present mathematical model of proposed algorithm and also perform the simulation under IMT-2000 channel models. Numerical results show that our proposed scheme outperforms the conventional one by 0.2 - 0.4 sec with respect to the mean code acquisition time because the soft decision technique can mitigate the possible decline in search performance caused by the use of a hard-decision technique.

Performance Analysis of an Adaptive Hybrid Search Code Acquisition Algorithm for DS-CDMA Systems (DS-CDMA 시스템을 위한 적응 혼합 검색형 동기획득 알고리즘의 성능 분석)

  • Park Hyung rae;Yang Yeon sil
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.3C
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    • pp.83-91
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    • 2005
  • We analyze the performance of an adaptive hybrid search code acquisition algorithm for direct-sequence code division multiple access (DS-CDMA) systems under slowly-moving mobile environments. The code acquisition algorithm is designed to provide the desired feature of constant false alarm rate (CFAR) to cope with nonstationarity of the interference in CDMA forward links. An analytical expression for the mean acquisition time is first derived and the probabilities of detection, miss, and false alarm are then obtained for frequency-selective Rayleigh fading environments. The fading envelope of a received signal is assumed to be constant over the duration of post-detection integration (PDI), considering slow fading environments. Finally, the performance of the designed code acquisition algorithm shall be evaluated numerically to examine the effect of some design parameters such as the sub-window size, size of the PDI, decision threshold, and so on, considering cdma2000 environments.

Performance Analysis of Burst-Format DS-SS Acquisition system Using a Serial-Maximum Likelihood Search- A Modified State Transition diagram Approach (직렬-최대 공차 탐색을 사용한 비스트형 DS-SS 초기 동기 시스템의 성능 분석-수정된 상태 천이도 접근법-)

  • 이독욱;김근묵;황금찬
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.28A no.11
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    • pp.855-865
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    • 1991
  • A simple method for analysis of serial search burst-format direct-sequence spread-spectrum (DS-SS) code acquisition system had been recently proposed, and therein, the effect of the code autocorrelation sidelobes on the performance of DS-SS code acquisition system has been assessed [4],[5]. In this paper, a new hybrid scheme which combines the serial search with maximum likelihood search is proposed to eliminate the deleterious effect of code autocorrelation sidelobes, and the performance is analyzed for the additive withe Gaussian noise (AWGN) channels. To analyze the performance of this system, we have generalized the method used in [4],[5] to arbitrary burst-format DS-SS acquisition schemes. The results show that a new hybrid scheme has good immunity against the effect of code autocorrelation sidelobes. Thevalidity of the presented approach has been confirmed form the results of simulation.

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Development of Unified SCADA System Based on IEC61850 in Wave-Offshore Wind Hybrid Power Generation System (파력-해상풍력 복합발전시스템의 IEC61850기반 통합 SCADA시스템 개발)

  • Lee, Jae-Kyu;Lee, Sang-Yub;Kim, Tae-Hyoung;Ham, Kyung-Sun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.5
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    • pp.811-818
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    • 2016
  • This paper suggests a structure of power control system in floating wave-offshore wind hybrid power generation system. We have developed an unified SCADA(Supervisory Control and Data Acquisition) system which can be used to monitor and control PCS(Power Conversion System) based on IEC61850. The SCADA system is essential to perform the algorithm like proportional distribution and data acquisition, monitoring, active power, reactive power control in hybrid power generation system. IEC61850 is an international standard for electrical substation automation systems. It was made to compensate the limitations of the legacy industrial protocols such as Modbus. In order to test the proposed SCADA system and algorithm, we have developed the wind-wave simulator based Modbus. We have designed a protocol conversion device based on real-time Linux for the communication between Modbus and IEC61850. In this study, SCADA system consists of four 3MW class wind turbines and twenty-four 100kW class wave force generator.

Acquisition Policy on Electronic Publications by the Natial Library of Korea toward Hybrid Library (하이브리드도서관을 지향하는 국립중앙도서관의 전자출판물 수집 정책)

  • 이숙현
    • Journal of the Korean BIBLIA Society for library and Information Science
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    • v.14 no.1
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    • pp.63-78
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    • 2003
  • Th term "hybrid library" refers to the collection of material in print, electronic and other media library hold and give access to. Hybrid library is the type of library that national library is toward in the digital age. Electronic publication is one of the important medias with the traditional media for hybrid library. This paper trys to introduce the acquisition policy on electronic publication by legal deposit, purchase, and other ways at the National Library of Korea with the trends of current electronic pulications domestically and internationally.ationally.

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Performance Comparison of Acquisition Schemes Using Multiple Antennas in DS-CDMA System) (DS-CDMA 시스템에서 다중 안테나를 이용한 동기획득방식의 성능비교)

  • Kang, Bub-Joo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.9A
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    • pp.1058-1066
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    • 2004
  • This paper proposes the acquisition system using the multiple antennas in DS-CDMA system. The conventional acquisition schemes using multiple antennas are the methods to utilize the multi-antenna combining and the fixed multi-beam forming of a serial acquisition. Then, this paper proposes the hybrid acquisition scheme using the fixed multi-beam forming. The numerical results show the performance comparison of two acquisition schemes in terms of the acquisition time ill the multipath Rayleigh fading channel.