• ETRI Journal
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• v.14 no.4
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• pp.1-9
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• 1992

본 고는 확산대역 시스팀에서 많이 사용되고 있는 상관기를 이용한 초기동기 장치의 하드웨어 복잡성과 초기동기에 소요되는 시간을 줄일 수 있는 부분 상관기를 제안하고 이의 성능을 컴퓨터 시뮬레이션을 통해 분석하였다. 시뮬레이션을 통하여 입력 SNR 에 따라서 부분상관기의 출력값을 분별지수로 구함으로써, 통신환경에 따른 적절한 부분 상관기의 길이를 구할 수 있었다. 즉 통신환경의 변화에 대해서 초기동기에 소요되는 시간과 하드웨어의 복잡성을 최대한 줄일 수 있는 상관기의 최적 길이를 구할 수 있었다.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.3
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• pp.39-44
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• 2001

In frequency hopping spread spectrum(FHSS) communication systems, exact frequency synchronization is required due to the random hopping of carrier frequencies between transmitter and receiver even under harsh channel conditions. For synchronization of FHSS communications, multi-frequency hopping synchronization(MFHS) method has been used in which a small set of frequencies are repeatedly sent several times for long duration. But this long duration resulted in being easily detected by the unauthorized users as well as long duration of acquisition time. In this paper, motivated by these problems, an adaptive synchronization method(ASM) is proposed. ASM is technics to reduce the synchronization time where the number of synchronization frequencies and repetition numbers is adaptively changed (increased or decreased) according to the channel conditions. The performance analysis showed that the time duration of synchronization was reduced to 0.2sec, and the influence of jamming or interference was decreased to 46% in ASM.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.1
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• pp.43-51
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• 1998

In this paper, the performance about the CDMA inital synchronization under the Rician fading channel, which is actively studied as a CAI for IMT2000(FPLMTS) is analyzed. Through the performance analysis with the double dwell serial search code acquisition, the minimum mean initial synchronization acquisition time vs signal detection threshold value and first dwell duration time respectively with parameters of false alarm probability, detection probability and test PN chips is presented and the results show the mean initial synchronization acquisition time is increased with lower slope than Rayleigh fading as the threshold value of the initial synchronization acquisition decision is increased.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.11
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• pp.28-36
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• 1998

In the CDMA mobile communication system with asynchronous mode among base stations, the initial PN code acquisition method using a matched filter can be considered for the rapid PN code synchronization acquisition in the handoff region. In the model of the noncoherent QPSK/DS-SS under the Rayleigh fading channel, the mean acquisttion time of the matched filter is analyzed to have a shortened time in proportion to the length of matched filter to be compared with the serial correlation method. In this paper to improve the HW complexity of the conventional matched device which enables the repeated correlation process, is designed and its function is verified through the FPGAsimulation using Altera MaxPlus Ⅱ.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.5
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• pp.12-20
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• 1999

본 논문에서는 DVB-T (digital video broadcasting-terrestrial) 수신기의 동기화 알고리듬과 각 동기단 사이의 연동 알고리듬을 제안한다. OFDM( orthohonal frequency division multiplexing) 수신단에서는 프레임 동기, 반송파 동기, 심볼 타이밍 동기가 요구되어진다. 기존의 반송파 동기 방법은 부반송파 간격의 정수배 주파수 옵셋 보상 후 잔존해 있는 주파수 옵셋이 -0.5×(부반송파 간격) 혹은 +0.5×(부반송파 간격)에 가까운 값을 가질 때 많은 시간이 소요되는 문제점을 가지고 있다. 본 논문에서는 시스템의 복잡도를 그대로 유지 하면서 초기 동기화 시간을 줄일 수 있는 반송파 동기 알고리듬을 제안한다. 그리고 DVB-T모드를 추정하는 알고리듬을 제안하고 반송파 동기 추적루프와 심볼 타이밍 동기 추적루프를 동시에 동작시킴으로써 초기 동기화 시간을 추가적으로 줄일 수 있는 심볼 타이ALD 동기 알고리듬을 제안한다. 그리고 전체 수신기 모델의 연동 방안을 제시한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.6
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• pp.105-114
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• 1984

A fast pseudo-noise (PN) sequence acquisition algorithm for the direct-sequence (DS) spread spectrum system is proposed. The basic concept of the algorithm has been adopted from that of the classical sliding correlator. Mathematical modeling, analysis and computer simulation of the proposed system have been done. The results of analysis and computer simulation show that the acquisition system yields a significant performance improvement over the sliding correlator. Its acquisition time takes only 45 ms when signal-to-noise ratio(SNR) is -18dB. The algorithm developed has been implemented in hardware and its experimental result is also given.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1A
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• pp.73-81
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• 2012

In this paper, we propose a high-speed synchronization method for Digital Radio Mondiale (DRM) receivers. In order to satisfy the high-speed synchronization requirement of DRM receivers, the proposed method eliminate the initial sampling frequency synchronization process in conventional synchronization methods. In the proposed method, sampling frequency tracking is performed after integer frequency synchronization and frame synchronization. Different correlation algorithms are applied to detect the first frame of the Orthogonal Frequency Division Multiplexing (OFDM) demodulation symbol with sampling frequency offset (SFO). A frame detection algorithm that is robust to SFO is selected based on the performance analysis and simulation. Simulation results show that the proposed method reduces the time spent for initial sampling frequency synchronization even if SFO is present in the DRM signal. In addition, it is verify that inter-cell differential correlation used between reference cells is roubst to the effect of initial SFO.