Receiver design and performance analysis for code-multiplexed transmitted-reference ultra-wideband systems
Author(s)
Advisor
Gezici, SinanDate
2010Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
In transmitted-reference (TR) and frequency-shifted reference (FSR) ultrawideband
(UWB) systems, data and reference signals are shifted relative to each
other in time and frequency domains, respectively. The main advantage of these
systems is that they remove strict requirements of channel estimation. In order
to implement TR UWB systems, an analog delay line, which is difficult to build
in an integrated fashion, is needed. Although FSR systems require frequency
conversion at the receiver, which is much simpler in practice, they have data rate
limitations. Instead, a code-multiplexed transmitted-reference (CM-TR) UWB
system that transmits data and reference signals using two distinct orthogonal
codes can be considered. This system requires a simpler receiver and has better
performance than TR and FSR.
In the first part of the thesis, CM-TR systems are investigated and probability
of error expressions are obtained. For the single user case, a closed-form
expression for the exact probability of error is derived. For the multiuser case, a
closed-form expression is derived based on the Gaussian approximation, and the
results are compared in different scenarios. In the second part of the thesis, some
optimal and suboptimal receivers are studied. First, low complexity receivers,
such as the blinking receiver (BR) and the chip discriminator, are presented. The
requirements for these types of receivers are explained, and the conditions under
which their performance can be improved are discussed. Then, an analytical
analysis of the linear minimum mean-squared error (MMSE) receiver and the requirements
to implement this MMSE receiver are provided. Lastly, the optimal
maximum-likelihood (ML) detector is derived, which has higher computational
complexity and more strict requirements than the other receivers. Finally, simulation
results are presented in order to verify the theoretical results and to
compare the performance of the receivers.
Keywords
Ultra-wideband (UWB)impulse radio (IR)
multiple-access interference (MAI)
transmitted-reference (TR)
frequency-shifted reference (FSR)
coded-multiplexed transmitted-reference (CM-TR)
blinking receivers (BR)
chip discriminator
linear MMSE
maximum-likelihood (ML)