• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.153-158
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• 2005

In this paper, an improved detection method is Proposed by supplementing multi-path gain for a MMSE detecter. This method is Proposed to complement the shortcomings of the conventional detection method which is used for multiuser detection in STBC CDMA system. We analyzed the improved method in bit error Probability viewpoint and compared the result with that of the conventional method In this result, we showed that the improved method obtains better performance of bit error probability than the conventional method when parameters such as delay, number of user and SNR are increased.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.257-262
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• 2010

In this paper, we propose an effective method for detecting signals among multi-user in cooperative communication system. Spread sequence is inserted to NULL space of synchronization channel to synchronize between each user among frame formats of the cooperative communication and then transmitted. In the receiver, the wanted signal is detected by using correlation among the inserted spread sequences. As simulation results, correlations among the signals using m-sequence in AWGN, Rician, and Rayleigh channel are shown. Using the simulation results in this paper, we expect a reliable cooperative communication.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.22-26
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• 2010

In this paper, we propose an effective method for detecting signals among multi-user in cooperative communication system. Spread sequence is inserted to NULL space of synchronization channel to synchronize between each user among frame formats of the cooperative communication and then transmitted. In the receiver, the wanted signal is detected by using correlation among the inserted spread sequences. As simulation results, correlations among the signals using Kasami/Walsh sequence in AWGN, Rician, and Rayleigh channel are shown. Using the simulation results in this paper, we expect a reliable cooperative communication.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.1-8
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• 1998

This paper presents an asynchronous DS/CDMA multiuser detector, which is a two stage, symbol-by-symbol scheme consisting of conventional detectors followed by linear decorrelating detectors. The conventional detector first makes temporal decisions and the detected symbols are delayed by one symbol period to be used for the selection of decorrelating bases in the subsequent decorrelaing detection stage. It also employs a bank of early-late correlators in place of a bank of single correlators taking the small offset of chip timing asynchronism into account. The proposed detector requires only the coarse knowledge of relative time delays of interfering users and is suitable for digital implementation. To verify the detector performance, the analytical BER performance will be given and compared with the simulation results for BPSK DS/CDMA signals in AWGN channel. While the performance of the proposed detector will be analyzed for time-limited signal, the simulation is carried out for both the time-limited and band-limited signals. As can be seen in the simulation results, the proposed scheme shows good results.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.213-221
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• 2006

In this paper, an improved detection method is proposed by supplementing various types of Proportional gam for a MMSE detecter. This method is proposed io complement the shortcomings of the conventional detection method which is used for multiuser detection in STBC(Space-Time Block Code) CDMA system. We analyzed the improved method in bit error probability viewpoint and compared the result with that of the conventional method. In this result, we showed that the Improved method obtains better performance of bit error probability than the conventional method when parameters such as delay, number of user and SNR are increased.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.355-358
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• 2000

기존의 Rayleigh fading 환경에서 칼만 필터를 사용한 다중 사용자 검출에서는 비동기적으로 들어온 다른 사용자 신호의 상태가 바뀜에 따라서 수렴하던 신호에 영향을 미친다. 이러한 특성은 결국 전체 시스템에 영향을 미쳐서 검출 성능을 떨어뜨린다. 본 논문에서는 에러가 발생하였을 때의 경우를 고려하기 위해 VFF(Variable forgetting factor)를 도입하였고 이를 이용해 추정된 신호의 가중 합을 기반으로 시스템을 구성한 결과 성능이 향상되었음을 보이고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.324-330
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• 2002

In this paper, we proposed a simple modification on Fiebig's REC algorithm for multiuser detection of FH/MFSK systems replacing hard limiter with soft limiter. The performance improvement of our modified REC algorithm has been confirmed with computer simulations. for the parameter of interest, the capacity could be increased about 5% or more without degrading the reliability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.4
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• pp.180-187
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• 2014

In this paper, a extension of a fixed-complexity sphere decoder (FSD) to perform interference signal detection and cancelling is proposed for downlink multiuser multiple input-multiple output (MIMO) communication system. It is based on the application of channel matrix expansion on generalized sphere decoder (GSD), and modification of the channel matrix ordering scheme to a FSD algorithm for interference detection. A Monte Carlo simulation shows that the proposed algorithm improves the receiver performance by 3 dB as compared to maximum likelihood detection without interference cancelling at 10% packet error rate in configuration of 702 Mbit/s datarate for four users respectively on IEEE802.11ac.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.98-100
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• 2010

본 논문에서는 주파수 선택적 페이딩(frequency selective fading) 채널에서 다중 사용자 MIMO-OFDM 시스템을 위한 자원 할당(resource allocation)을 연구한다. 다중 사용자의 신호를 검출하기 위해 기지국은 MMSE-SIC 수신기를 사용하고 이러한 조건에서 다중 사용자 MIMO-OFDM 시스템을 위한 최적화 문제를 도출하며 이를 위한 자원 할당 기법을 제안한다. 평균 채널 이득이 사용자마다 다른 환경에서의 컴퓨터 모의실험을 통해 제안된 자원 할당 기법의 성능을 알아본다. 모의 실험 결과 제안된 자원 할당 기법은 기존의 자원 할당 기법보다 더 높은 데이터 전송률(data rate)을 달성함을 보이고 있다.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.651-658
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• 2020

In the fifth generation (5G) mobile networks, the interactive mobile game users have increased tremendously, which induces correlated information sources (CIS). One of the promising 5G technologies is non-orthogonal multiple access (NOMA). In NOMA, the users share the channel resources, so that CIS affect each user's bit-error rate (BER) performance, which is not the case for orthogonal multiple access (OMA). In this paper, we derive the optimal receiver for NOMA with CIS, and then investigate the impact of CIS on each user's BER performance.