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Multiuser Interference (multiuser + interference)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

Interference reduction in synchronous fiber-optic PPM,CDMA systems

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2001
T. S. Lee
Abstract A pulse-position modulation (PPM) optical CDMA system with interference estimation and cancellation is proposed. Multiuser interference is estimated with the aid of modified prime code sequence properties. A comparison between the bit-error rate (BER) of both the proposed system and the system without cancellation reveals that the former system improves the BER performance significantly. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 202,205, 2001. [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]

Load-Adaptive MUI/ISI-Resilient Generalized Multi-Carrier CDMA with Linear and DF Receivers

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2000
Georgios B. Giannakis
A plethora of single-carrier and multi-carrier (MC) CDMA systems have been proposed recently to mitigate intersymbol interference (ISI) and eliminate multiuser interference (MUI). We present a unifying all-digital Generalized Multicanier CDMA framework which enables us to describe existing CDMA schemes and to highlight thorny problems associated with them. To improve the bit error rate (BER) performance of existing schemes, we design block FIR transmitters and decision feedback (DF) receivers based on an inner-code/outer-code principle, which guarantees MUI/ISI-elimination regardless of the frequency-selective physical channel. The flexibility of our framework allows further BER enhancements by taking into account the load in the system (number of active users), while blind channel estimation results in bandwidth savings. Simulations illustrate the superiority of our framework over competing MC CDMA alternatives especially in the presence of uplink multipath channels. [source]