Multiple-input multiple-output (MIMO) systems have received much attention due to their
multiplexing and diversity capabilities. It is possible to obtain remarkable improvement
in spectral efficiency for wireless systems by using MIMO based schemes. However, sophisticated
equalization and decoding structures are required for reliable communication at
high rates. In this thesis, capacity achieving practical transceiver structures are proposed for
MIMO wireless channels depending on the availability of channel state information at the
transmitter (CSIT).
First, an adaptive MIMO scheme based on the use of quantized CSIT and reduced precoding
idea is proposed. With the help of a very tight analytical upper bound obtained for limited
rate feedback (LRF) MIMO capacity, it is possible to construct an adaptive scheme varying
the number of beamformers used according to the average SNR value. It is shown that
this strategy always results in a significantly higher achievable rate than that of the schemes
which does not use CSIT, if the number of transmit antennas is greater than that of receive
antennas.
Secondly, it is known that the use of CSIT does not bring significant improvement over
capacity, when similar number of transmit and receive antennas are used / on the other hand,
it reduces the complexity of demodulation at the receiver by converting the channel into noninterfering
subchannels. However, it is shown in this thesis that it is still possible to achieve
a performance very close to the outage probability and exploit the space-frequency diversity
benefits of the wireless fading channel without compromising the receiver complexity, even
if the CSIT is not used. The proposed receiver structure is based on iterative forward and
backward filtering to suppress the interference both in time and space followed by a spacetime
decoder. The rotation of multidimensional constellations for block fading channels and
the single-carrier frequency domain equalization (SC-FDE) technique for wideband MIMO
channels are studied as example applications.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12610398/index.pdf |
| Date | 01 February 2009 |
| Creators | Guvensen, Gokhan Muzaffer |
| Contributors | Yilmaz, Ali Ozgur |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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