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Multiuser Detector (multiuser + detector)

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Engineering100%

Selected Abstracts

Fuzzy-based multiuser detector for impulsive CDMA channel

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 7 2007
Adel M. Hmidat
A new fuzzy multiuser detector for non-Gaussian synchronous direct sequence code division multiple access (DS-CDMA) is proposed for jointly mitigating the effects of impulsive noise and multiple access interference (MAI). The proposed scheme combines a linear decorrelator and antenna array with a nonlinear preprocessor based on fuzzy logic and rank ordering. The fuzzy rule is incorporated to combat impulsive noise by eliminating outliers from the received signal. The performance of the proposed scheme is assessed by Monte Carlo simulations and the obtained results demonstrate that the proposed fuzzy detector outperforms other reported schemes in terms of bit error rate (BER) and channel capacity. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Joint data detection and estimation of time-varying multipath rayleigh fading channels in asynchronous DS-CDMA systems with long spreading sequences,

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 2 2007
Pei Xiao
In this paper, we present a joint approach to data detection and channel estimation for the asynchronous direct-sequence code-division multiple access (DS-CDMA) systems employing orthogonal signaling formats and long scrambling codes. Our emphasis is placed on different channel estimation algorithms since the performance of a communication system depends largely on its ability to retrieve an accurate measurement of the underlying channel. We investigate channel estimation algorithms under different conditions. The estimated channel information is used to enable coherent data detection to combat the detrimental effect of the multiuser interference and the multipath propagation of the transmitted signal. In the considered multiuser detector, we mainly use interference cancellation techniques, which are suitable for long-code CDMA systems. Interference cancellation and channel estimation using soft estimates of the transmitted signal is also proposed in this paper. Different channel estimation schemes are evaluated and compared in terms of mean square error (MSE) of channel estimation and bit error rate (BER) performance. Based on our analysis and numerical results, some recommendations are made on how to choose appropriate channel estimators in practical systems. Copyright © 2006 AEIT [source]

Multistage multiuser detector for multipath fading channel

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2001
Dejan M. Novakovi
In this paper, the multistage multiuser detector for communication over multipath fading channel is considered. The detector consists of a matched filters bank and a linear equalizer whose outputs are diversity combined to produce initial data estimates. Using these data estimates multiuser interference is reconstructed and removed from the output signals of the matched filters bank. Afterward, diversity combining is applied again and it produces final decision statistics. Simulation results indicate that this detector outperforms conventional RAKE receiver and the linear equalizer with diversity combining. Also, the proposed detector is near,far resistant. [source]

Selective partial PIC for wireless CDMA communications

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2003
Filippo Belloni
Abstract This paper deals with a cancellation multiuser detector for CDMA communication systems. The proposed receiver, defined as selective partial parallel interference cancellation (SP-PIC), is supposed to be used at the end of an up-link channel characterized by multipath fading phenomena. The SP-PIC main feature is to perform a weighted selective cancellation of the co-channel interfering signals according to the received power level. With respect to other approaches, the proposed detector exhibits an improved bit error rate (BER) and a low computational complexity, linear with the number of users. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Asynchronous orthogonal decision-feedback multiuser detector (AODFD) and its alternative decoding strategies

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2001
Hsiao-Hwa Chen
Abstract This paper proposes a new CDMA multiuser detector, asynchronous orthogonal decision-feedback detector (AODFD), and its alternative decoding schemes. The proposed AODFD does not require an infinitely long whiten filter in its feed-forward stage, however, which is necessary in the traditional ADDFD detector reported in the literature. The updating algorithm of the AODFD detector is also much simplified if compared with that of ADDFD that requires computational intensive z -transformed matrix inversion and spectral factorization. Results show that, despite its low complexity, the AODFD performs very well under multiple access interference. The proposed two new decoding strategies can also be chosen to cater for different operating scenarios. Copyright © 2001 John Wiley & Sons, Ltd. [source]