| Summary: | 碩士 === 元智大學 === 電資與資訊工程研究所 === 86 === In this thesis, we consider the problems of wireless mobile
communication system under the difficult situation like
combined realistic fast Rayleigh fading, frequency selective
channel and the presence of co-channel interference (CCI) by
using smart antenna technique to improve both the performance
and capacity. In contrary to the conventional digital beam-
forming technique which adjusts the array weighting to specify
the beam pattern, our approach follows the concept of spatial
diversity combination and extends it to space-time processing
(STP) for dealing with such difficult cases.
The proposed method uses the adaptive spatial and temporal
combining antenna array to combat frequency selective fast
fading and suppress CCI. A short known training sequence is
used for determining the space-time processor weights
periodically by a RLS algorithm and decision-directed mode is
used to keep track of channel variation during data
transmission. The STP structure used is a sum of T/2-spaced
tapped delay line filters following after the antennas, then
connected with an optional T-spaced decision-feedback filter.
As expected, this structure behaves better than T-spaced STP
and is also insensitive to the timing phase error.
Furthermore, we also formulate the multi-user detection
problem where multiple signals of interest are transmitted
on the same frequency band and to be detected at the same time.
In such a case, we present a STP technique, which incorporates
a CCI cancellation method to predict the CCI and cancel it.
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