الفهرس 
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Abstract
This thesis treats some modeling and estimation problems in the
field of antenna array signal processing. With multiple antennas at the
receive side, the spatial dimension is added, and processing is performed
in both the temporal and spatial domain. The work is motivated by the
interest in using antenna arrays, primarily at the base stations, in wireless
communication systems. Among the potential benefits are increased
range, fading diversity, interference rejection and spatially selective
transmission.
The thesis is divided into two parts: spatial and spatial-temporal
processing parts. The first part focuses on the problem of estimating the
channel parameters i.e. Direction Of Arrival (DOA) referred as spatial
signatures for a uniform linear array. Different algorithms for estimating
the DOAs of the signals received at the array are provided and
investigated. Both of narrowband and wideband signals either
uncorrelated or coherent are considered. Performance comparisons
between these DOA algorithms for different signal types are performed.
It was shown that when the spatial-only models are used to deal with the
coherent signals as in multipath environments, most of DOA methods
may probably fail. This is because the signal models are assumed to be
narrowband with inverse bandwidth small in comparison to the time
dispersion introduced by the propagation as well as the channels are
modeled as non-frequency selective with small angular spread .
AJso, the DOA estimation in different propagation environments
such open, urban, suburban, and urban areas are studied. It is proved that
the DOA estimation accuracy depends on environment type. The
simulation shows that better DOA estimations can be obtained in simple
propagation environments such as open and suburban areas while lesser
accuracy is achieved in complicated one such as urban areas. This is
because the Signal to Noise Ratios (SNRs) obtained in complicated
propagation areas are lower than that obtained in simple propagation one.
Some improvements can be performed by increasing the antenna gain and
power output of base station.
The second part investigates a DS-CDMA system that employs
antenna array receivers. The users are separated by different short
periodic Pseudo Noise (PN) codes. The inherent spatial and temporal
structure in the received user signals is exploited in order to combat Intersymbol Interference (lSI) introduced by a multi path channel as well
as to mitigate MUltiple Access Interference (MAl) imposed by the multi
access system. Various blind single-user receivers are presented which
have only the knowledge of the PN code of the desired user. They are
compared and assessed, both theoretically with a mathematical
framework and practically with simulation results. It is shown how
conventional time-only or space-only methods can be unified and
regarded from. a space-time point of view. In particular, conventional
receivers based on matched filters like, e.g., the RAKE receiver are put
into a space-time context and compared to the relatively new subspacebased
method, which does not entirely rely on the mutual orthogonality of
the signals but exploits their linear independence. Two separate aspects of
the receiver are emphasized: the estimation part, which is in charge of
providing the channel parameters associated with the user of interest, and
the reception part, which separates the desired from the undesired signal
components based on the estimated parameters.
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