• 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 Communications and Information Sciences
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• v.31 no.5A
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• pp.501-508
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• 2006

Orthogonal frequency division multiplexing-code division multiplexing access(OFDM-CDMA) systems without guard interval can enhance the bandwidth performance more efficiently than the systems with guard interval. In this paper, a new technique for an OFDM-CDMA system without guard interval, which can eliminate inter-symbol interference(ISI) and inter-channel interference(ICI), is presented. The proposed algorithm is a new demodulation technique, based on the Pseudo-Decorrelator, and it is named PD algorithm. Simulation results show that the PD algorithm can combat ISI and ICI efficiently for an OFDM-CDMA system without guard interval. The BER performance of the PD algorithm is much better than that of a conventional OFDM-CDMA system without guard interval.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5A
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• pp.382-388
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• 2005

An OFDM system may be a good candidate for a next-generation wireless communication system which requires high-speed and high-rate data transmission. In OFDM systems, guard intervals are inserted to mitigate the effects of ISI (Inter-Symbol Interference). But guard interval insertion degrades the system performance from the standpoint of data rate and bandwidth efficiency. In this paper, a new method to improve the performance of an OFDM system without guard interval. First, PIC (Parallel Interference Cancellation) scheme which can reduce ISI by subtracting the estimated multi-path components from the received signal will be considered. And the proposed system with Pseudo-Decorrelator estimates transmitted signals by using the inverse matrix of cross-correlation matrix relating to interference components. The performance of the proposed system is evaluated through computer simulations and compared with that of the PIC system and an OFDM system without guard interval.

• The Journal of the Acoustical Society of Korea
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• v.20 no.6
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• pp.87-93
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• 2001

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 receiver for WCDMA uplink systems over an additive white Gaussian noise 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. In this receiver, the detection process can be started after the first three consecutive bits are received. Simulation results are presented for K-user systems over an additive white Gaussian noise channel under the circumstances in which synchronization errors, including time delay errors and carrier phase errors exist. It is shown that the proposed receiver performs better than a conventional receiver and parallel interference canceller.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.5B
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• pp.645-652
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• 2001

본 논문에서는 일반적인 코드분할 다중화 시스템을 위해 저자가 제안하였던 유사 역상관기 (Pseudo-Decorrelator)를 변형하여 WCDMA 시스템에 적합한 원근 저항성 (near-far resistant) 수신기를 설계하고, 임펄스 채널 환경에서 성능을 분석하고 있다. 설계된 수신기에서는 판단변수 (decision statistics)에 포함되어 있는 다중사용자 간섭신호를 분석하여, 송신된 신호의 각 비트에 대응되는 상호상관 행렬을 얻게 된다. 이 상호상관 행렬을 역변환 시킨 후, 기존의 수신기에서 얻어진 판단변수에 적용한다. 이렇게 해서 수신기의 성능을 향상시킬 수 있다. 제안된 수신기는 연속해서 3비트를 받은 후에 바로 검출과정 (detection process)을 수행할 수 있다는 잇점이 있다. 임펄스 채널에서의 여러 가지 시뮬레이션을 통해서 수신기의 성능이 향상됨을 확인할 수 있었다.