On the Downlink Spectral Efficiency of DS-CDMA Systems Using MMSE Detectors
نویسندگان
چکیده
The spectral efficiency of single-cell DSCDMA systems deploying higher order modulation schemes is investigated for the downlink in presence of fading channels. Therefore, the asymptotic analysis (AA) is evaluated for random and orthogonal Haar distributed spreading codes to obtain the signal-to-interference-andnoise ratio (SINR) after the optimal and a suboptimal linear MMSE detector. An extension to the AA is proposed for both receiver structures to include the intersymbol interference, which is shown by means of simulations to significantly improve the results for multipath fading channels. Based on the extension, the SINR can be used in conjunction with measures of the information theory to determine the spectral efficiency of the system. For modulation and coding at the cut-off rate the tradeoff between multi-code transmission and higher order modulation is investigated. Furthermore, an efficiency comparison between the suboptimal and the optimal LMMSE is conducted.
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تاریخ انتشار 2005