The use of an antenna array for parameter estimation and detection in DS -CDMA communication systems.

摘要

The use of antenna arrays is a promising technology for improving performance of all types of cellular networks. This dissertation investigates the use of multiple antenna sensors for parameter estimation and detection in Direct-Sequence Code-Division Multiple-Access (DS-CDMA) communication systems. Our focus is on the timing estimation that is essential for any type of DS-CDMA system. In order to increase the performance and capacity of the DS-CDMA system, the use of an adaptive antenna array and diversity combiner has received much attention, but there has been less attention to the code timing estimation problem when using multiple antenna sensor arrays.;We describe a general spatial channel model for exploiting multiple antenna sensors at the base station. Tap weight vector estimator for beamforming or diversity combining is proposed and evaluated. We derive the Cramer-Rao Bound (CRB) for the parameter estimation problem when using multiple antenna sensors. The code timing estimation problem with multiple antenna sensors is introduced. The adaptive antenna array and diversity combiner based code timing estimation schemes are proposed and studied. The proposed approach for estimating the code timing is shown to improve the performance of a single antenna based timing estimator in both fading and nonfading conditions when we use an existing CDMA system's standard power control technique. The problem of estimating multipath timings of DS-CDMA signals when using a multiple antenna sensor array which exploits spatial diversity is also considered on a frequency selective fading channel.;The minimum mean-squared error (MMSE) receiver is a very attractive receiver for the DS-CDMA signal detection. We study the effect of the multiple antenna sensors on the MMSE detector over fading channels.