This thesis analyzes and quantifes the performance of adaptive orthogonal
frequency division multiplexing (OFDM) systems in conjunction with single
and multi antenna systems operating over frequency selective Rayleigh and
Rician fading environments. We introduce a generalized transceiver model for
adaptive cyclic prefixed (CP)-OFDM and isotropic orthogonal transform algorithm (IOTA)-OFDM. Fundamental issues concerning the BER performance
of CP-OFDM and IOTA-OFDM are investigated under typical system imperfections. Furthermore, a throughput comparison of these two types of adaptive
systems is given. Next, the peak-to-average power ratio (PAPR) problem of
adaptive OFDM is considered. Focusing on wideband channel variations in
the frequency domain, we have developed a novel statistical analysis for adaptive multiple input multiple output (MIMO)-OFDM systems. In addition, a
central limit theorem (CLT) was developed for a wide range of block-based
performance metrics.
This thesis aims to present a systematic study of channel variation with a
statistical analysis of the MIMO-OFDM channel and system performance. In
particular, we focus on the behavior of block based performance measurements
by considering the correlation across the frequency bins of the OFDM block.
In addition, we investigate the eigenvalue variation of MIMO-OFDM systems
across frequency. We show that eigenvalue and link gain changes in frequency
can be analyzed and have presented novel results on the distributions and moments of such changes. We have also given expressions for the autocorrelationfunctions (ACFs) of the maximum eigenvalue and the link gain. Of particular
interest is the very simple approximation to the ACF of the maximum eigenvalue. This leads to accurate closed-form approximations to the variance and
CDF of the eigenvalue differences.
We consider three types of adaptive MIMO-OFDM systems; one is based on
(diversity mode) maximal ratio transmission-maximal ratio combining (MRT-
MRC), while the others are spatial multiplexing techniques using singular value
decomposition (SVD) or minimum mean square error (MMSE) receivers with
linear precoding. We derive closed-form expressions for the joint cumulative
distribution function (CDF) of arbitrarily selected eigenvalues in the same bin
and in different bins. Furthermore, for MIMO with MRT-MRC, and MIMO-
SVD, the exact mean and variance of the number of bits transmitted per
OFDM block has been computed analytically and veried with Monte Carlo
simulations.
| Identifer | oai:union.ndltd.org:canterbury.ac.nz/oai:ir.canterbury.ac.nz:10092/3835 |
| Date | January 2009 |
| Creators | Kongara, Krishna Prasad |
| Publisher | University of Canterbury. Electrical and Computer Engineering |
| Source Sets | University of Canterbury |
| Language | English |
| Detected Language | English |
| Type | Electronic thesis or dissertation, Text |
| Rights | Copyright Krishna Prasad Kongara, http://library.canterbury.ac.nz/thesis/etheses_copyright.shtml |
| Relation | NZCU |
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