Study of Low Complexity Multiuser Receiver Design for Space-Time Coded Code Division Multiple Access Systems

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Date

2007-07

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Addis Ababa University

Abstract

The goal for the next generation mobile communication systems based on CDMA is to integrate a wide variety of communication services such as high speed data, video and multimedia traffic as well as voice signals. To effect these services, high rate data transmission and reception techniques are required. As demands for communication services increase, there is considerable economic benefit in improving the spectral efficiency of the communication system. One of the proposed approaches for these high data rate and spectrally efficient transmission in CDMA systems is space-time coding. The use of space-time coding techniques in CDMA systems increases multiuser interference. The effect of multiple access interference can be mitigated by using multiuser receivers. Multiuser receivers in STC CDMA systems have been shown to provide significant improvements in spectral efficiency. However, despite the great promises, these receivers have not been widely deployed in commercial communication systems. This lack of commercial interest is partly because of issues related to receiver complexity. Thus using analysis, reasonable approximations and simulation, this work attempts to realize a lower complexity multiuser receiver for STTC DS-CDMA systems. The complexity is reduced by dividing the users into groups having smaller trellises. The simulation results show that the proposed receiver performs close to the optimal receiver even at high cross correlations of the spreading sequences with a reduced complexity. Keywords: CDMA, Spreading Sequences, Space-Time Coding, Fading Channels, Multiple Access Interference multiuser detection

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Keywords

Cdma, Spreading Sequences, Space-Time Coding, Fading Channels, Multiple Access Interference Multiuser Detection

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