• Journal of Broadcast Engineering
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• v.19 no.2
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• pp.272-275
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• 2014

In this paper, the spectrum sharing cognitive radio network is investigated. For assuming that channels for the secondary network are double Rayleigh fading channels, we derive the exact and the approximate outage probabilities. Numerical results verify the validity of our theoretical analysis by comparison with Monte Carlo simulation results.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.233-236
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• 2000

In this paper, we consider a code acquisition of W-CDMA signals over multipath Rayleigh fading channel when double-dwell serial search code acquisition is used for initial synchronization. We derive the detection and false alarm probability, and mean acquisition time mathematically by taking into account of multiple H$_1$ cells and double-dwell serial search. It is noteworthy that the more the number of the post-detection integration, the shorter the mean acquisition time in low SNR.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1432-1435
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• 2002

Performance of conventional PN acquisition schemes deteriorates when it is used in a fading channel. A new modified PN acquisition scheme is proposed to improve that performance in a frequency-selective fading channel. Simulation is used for verifying the performance which shows that the new scheme outper-forms the convention PN acquisition scheme using similar hardware.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.51-55
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• 2015

In this paper, we proposed scheme that obtain diversity gain in the cooperative communication to mitigate, applied to the effects of fading in the vehicle communication. Relay used bus that can available in the city environment. In addition, we applied the double rayleigh fading environment so that can applied in real-environments. Therefore, proposed scheme through this paper applied to vehicle communication, user can acquire a high quality service and the operation efficiency of the network is improved. Finally, performance of the proposed protocol is analyzed in terms of bit error rate.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.189-192
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• 2000

In this paper, we consider a code acquisition of W-CDMA signals over multipath Rayleigh fading channel when double-dwell serial search code acquisition is used for initial synchronization. We derive the detection and false alarm probability, and mean acquisition time mathematically by taking into account of multiple H$\_$l/ cells and double-dwell serial search. It is noteworthy that the more the number of the post-detection integration, the shorter the mean acquisition time in low SNR.

• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.677-680
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• 2015

In this paper, we propsed scheme to mitigate conflict and loss of message in vehicle communication. And vehicles that exist in the moving direction, were grouping to the cluster form. Through, to select best relay vehicle, transmit a message to the destination. In addition, we applied the double rayleigh fading environment so that can applied in real-environments. Therefore, vehicle communication network applied proposed scheme, can be problem of mitigate conflict and loss of message. Thus, Increase the reliability of the received signal.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.270-275
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• 2010

In a conventional opportunistic transmit (COT) cooperative relaying system, only the relays that receive signal-to-noise ratio (SNR) from the source and that exceed the threshold transmit to the destination. The COT system, however, only considers the SNR of the source-relay (S-R) path regardless that the SNR of the relay-destination (R-D) path is the opportunistic transmission condition. For that reason, it is not guaranteed that all the transmitted signals from relays exceed the threshold at the destination. Therefore we propose a double opportunistic transmit (DOT) cooperative relaying system - when both of the received SNR from a source and from a destination exceed the threshold, the relay transmits to the destination. It is shown that the proposed DOT system reduces power consumption by 6.9, 20.9, 32.4, and 41.4 % for K =3, 5, 7, and 9, respectively under the given condition of $P_{out}=1{\times}10^{-3}$ and $\overline{\gamma}_{SR}/\Gamma_{SR}$=30 dB, compared to the COT system. We noticed that the performance of the DOT system is superior to that of the COT system for the identical number of active transmit relays under the same condition of the normalized average SNR of $\overline{\gamma}_{RD}/\Gamma_{RD}$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1237-1242
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• 2007

In this paper, we study STBC(Space Time Block Code) detection scheme in time varying Rayleigh fading channel. When the channel is varying during the time duration of STBC, the channel matrix of orthogonal STBC is not orthogonal. To get the optimum reception performance in this channel, joint ML detection scheme may be used, however this scheme requires high computation complexity. Decision feedback scheme is proposed to reduce the computation complexity with less reception performance. In this paper, we propose a novel STBC detection algorithm using double decision feedback which is less complex than the joint ML scheme and outperforms the conventional decision feedback scheme.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.248-249
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• 2014

기존 연구에서 무선 인지 네트워크의 성능 분석에 관한 연구는 많았지만 다중 사용자가 존재하는 무선 인지 네트워크에 차량 통신을 접목시킨 무선 인지 차량 네트워크의 성능 분석에 관한 연구는 많지 않았다. 또한 최근 실질적인 채널환경을 고려하기 위해 지연된 채널 상태 정보를 가진 시스템에서의 성능 분석에 대한 연구가 많이 진행되고 있는데, 다중 중계기가 존재하는 무선 인지 차량 네트워크에서 지연된 채널 상태 정보의 영향에 대한 연구는 아직 진행되지 않았다. 본 논문에서는 다중 중계기가 존재하는 무선 인지 차량 네트워크에서 지연된 채널 상태 정보의 영향을 분석한다. 본 논문에서는 스펙트럼 공유(spectrum sharing) 무선 인지 네트워크를 가정하고 차량간 통신이 일어나는 2차 사용자 네트워크의 채널들을 double Rayleigh fading으로 모델링 한다. 성능 분석의 지표로 불능 확률을 사용하고 컴퓨터 모의실험을 통해 지연된 채널 상태 정보의 영향을 확인한다.