• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.885-892
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• 2000

A multi-used detector(MUD) using a radial basis function(RBF) network is proposed in a multicarrier-code division multiple access (MC-CDMA) system. In the proposed scheme, a RBF network is connected to the frequency domain in order to effectively utilize the frequency diversity. Simulations have been performed over the frequency selective and multipath fading channel. From these simulations, the proposed receiver is verified to be used for making the performance improvement in combating near-far effects and increasing the number of active users. The system capacity is increaed about 1.8 times at a BER of $10^{-3}$ under a single cell when the proposed scheme is compared with MUD using a parallel interference canceller(PIC).

• Journal of Korea Multimedia Society
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• v.5 no.5
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• pp.582-589
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• 2002

In this paper, we propose a new method that combines antenna array, which employs any beamforming algorithm, and successive interference cancelling multiuser detector which improves the performance of the receiver and analyse its performance. Antenna away receivers can improve the performance by spatially discriminating among the users and reducing the multiple access interference. But the performance of the receivers degrades when the difference of the direction of arrival of the users are too small. Many interference cancelling multiuser detectors have been suggested for DS/CDMA systems which have low complexity for their performance. In this paper, we show how to mitigate such a degradation by combining successive interference cancelling multiuser detector.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.120-127
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• 2002

As a new type of a linear decorrelating receiver, the Pseudo-Decorrelator was presented for asynchronous code division multiple access systems by the author. In this paper, the concept of the Pseudo-Decorrelator is extended to derive a multiuser receiver for WCDMA uplink systems over a Rayleigh fading multipath channel. Starting with the analysis of the multiple access components of the decision statistics, a non-square cross-correlation matrix for each bit is obtained. This cross-correlation matrix is then inverted, and the inverted matrix is applied to the decision statistics obtained from a conventional receiver. This receiver is near-far resistant and outperforms conventional receivers even for the cases in which synchronization errors, such as time delay errors and phase errors exist.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.589-599
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• 1997

In this paper a decision feedback multiuser receiver which rejects multiuser interference is designed in synchronous CDMA systems. Multiuser interference rejection is achieved by decision feedback from the output of a matched filter bank in case of AWGN channels and PAKE receiver bank in case of fading channels. The coefficients of the decision feedback structure are adapted by the Least Mean Square(LMS) algorithm. Simulation results show that the decision feedback multiuser receiver has better performance than the conventional receiver.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.11
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• pp.1-7
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• 2004

We propose multistage parallel nulling (MPN) partial parallel interference cancellation (PPIC) receiver for downlink multiple-input multiple-output (MIMO) multicarrier (MC)-code division multiple access (CDMA) systems. Though the V-BLAST is a popular MIMO receiver, it shows error floor for multiuser downlink MIMO MC-CDMA systems. The proposed MPN-PPIC receiver does not produce error floor for multiuser case, and achieves substantial performance gains with multistage processing. For single user case, the proposed method also surpasses the V-BLAST receiver with multistage processing for MIMO MC-CDMA systems with chip level interleaving. The system performance of the proposed MPN-PPIC receiver is evaluated through computer simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.674-681
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• 2006

In this paper, a new receiver with low complexity for a DS-UWB system which can eliminate efficiently the multiple access interference and the detrimental effects caused by multi-paths is proposed. The performance of conventional DS-UWB receivers depends greatly on the types and lengths of spreading codes. Generally, as the length of spreading codes increases, the receiver performance improves. But, the receiver performance does not improve satisfactorily in a multi-paths fading environment. Through computer simulations, it can be shown that the proposed DS-UWB receiver eliminate the multi-paths effects efficiently in a multi-user, multi-paths fading environment, and the user capacity can be increased dramatically using the proposed receiver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2C
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• pp.91-99
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• 2003

In this paper, We analyze performance of ZFE MUD receiver in DSSS unidirectional wireless transceiver operating in 2.4㎓ ISM band and indoor environment. This system has the shortcomings that many burst error is occurred because of long term deep fade experienced by some user and impossibility of power control. Therefore, the solution to this problem is important because the performance of DS-CDMA system is guaranteed under, the perfect power control. MUD receive. which improves the performance of this system is not required to perform rigorous power control and is able to remove MAI using linear equalization. From the result of performance comparison, we show that ZFE MUD receiver is more adequate for this system than other receivers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6A
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• pp.631-639
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• 2004

In this paper, we presented a new interference suppression method based on code grouping and groupwise decorrelation for multirate DS-CDMA downlink. The code grouping is accomplished according to the correlation property between the mother code and the child codes in OVSF code tree. Using groupwise decorrelation, the proposed receiver has relatively low computational complexity and does not require any information about interference users, such as code, data, and amplitude. From the simulation results in multipath channels, the proposed receiver is to provide significant performance enhancement.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.12-19
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• 2014

In this paper, an advanced UWB (ultra wideband) Rake receiving technique based on the statistical distribution model is studied in the M-ary TH-PPM system with multiple access interference (MAI). In order to improve the performance of the Rake receiver, the stochastic model, which can flexibly express the behavior of MAI-plus-noise, is required and the Laplace distribution and the generalized normal Laplace (GNL) model applied by the curtosis matching method are considered. The performance of Rake receiver based on each probability distribution is evaluated in the IEEE multipath fading channel and compared to that of the conventional Rake receiver. The suggested approach shows a superior BER performance than that of conventional Rake receiver.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.149-152
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• 2010

기존의 협력통신 관련 연구는 주로 단일 송 수신기와 다중 중계기가 존재하는 시스템 상에서 최적의 중계기를 선택하여 협력전송을 하거나 다중 중계기 모두를 이용한 협력통신이 이루어지고 반대로 단일 수신기, 중계기와 다중 송신기가 존재하는 시스템에서 최적의 사용자를 선택하는 것에 관한 것이 대부분 이었다. 하지만 실질적으로 보았을 때는 시스템 전체적인 관점에서 보았을 때 각각의 사용자에 대하여 최선의 중계기를 선택할 경우 오히려 전체적인 시스템 성능은 떨어질 수 있다. 본 논문에서는 다중사용자 협력시스템에서 각각의 사용자들이 자신들의 중계기 역할을 할 사용자를 선택하는 기법에 대하여 알아본다. 각 사용자에 대하여 자신이 중계기 역할을 할 경우 복호및재전송 기법을 이용하여 중계역할을 하고 그렇지 않을 경우 자신의 신호를 재전송한다. 제안된 시스템에서의 각 사용자에 대한 불능확률을 구하고 그것을 기반으로 사용자를 선택하게 된다. 모의실험을 통해 제안된 시스템에서의 사용자 선택 기법들의 성능을 알아보았고 이를 평균 불능확률로 나타내었다. 모의실험 결과 제안된 시스템에서 랜덤선택은 협력통신을 하지 않은 경우보다 안 좋은 성능을 보였고 나머지 기법들의 경우 협력통신을 하지 않은 경우보다 월등히 좋은 성능을 보였다.