Linear Multiuser Detection for Asynchronous DS-CDMA UWB in the Indoor Environments
Date Issued
2004
Date
2004
Author(s)
Chen, Chi-Hsien
DOI
en-US
Abstract
We demonstrate that the adaptive MMSE multiuser receiver can effectively gather multipath energy and eliminate the multiple-access, intersymbol and interchip interference for an ultra-wideband (UWB) pulse based direct sequence spread spectrum system using code division multiple access following on the early work [10]. A high level of multipath fragmentation caused by the fine path resolution of wideband (3.1-5.15 GHz) channel is the dominant problem, which we treat in this thesis. We prove that the adaptive implementation of MMSE receiver has the potential of providing the anticipated performance gains with a complexity that would be manageable. Also, we propose a noncoherent MMSE receiver if the channel phase is time-variant. We show that the noncoherent adaptive algorithms for filter adjustment can converge in the presence of phase variations, whereas their conventional counterparts diverge. Finally, we propose adaptive filter banks as the multiuser receiver for MBOK DS-CDMA UWB systems. We also compute the analytic performance of ideal MMSE for MBOK system from the idea of its special case, 2-BOK. The adaptive MMSE receiver shows only an additional decibel of loss over the ideal version. And the ideal MMSE receiver also showed only a 6-dB penalty versus the AWGN channel case. Hence, the regarded linear MBOK adaptive multiuser receiver is near-far resistant.
Subjects
超寬頻
多用戶偵訊
直序分碼多工
UWB
MUD
MBOK
DS-CDMA
Type
thesis
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