This dissertation presents the continued study of a
non-iterative decision feedback (DF) receiver/decoder
design and its application to cellular communications or
wireless local loop systems based on the IS-95(-A)
standard of the Telecommunications Industry Association
and also Personal Communications Services systems based on
the American National Standards Institute standard J-STD-
008-1996, which use code-division multiple access (CDMA)
spread spectrum technology. Specifically, the DF decoder
presented herein can be used in the uplink of these
systems, which simultaneously uses a concatenation of
convolutional coding, interleaving, and orthogonal Walsh
modulation.
The main contributions of this dissertation are the
demonstration that the DF concept works well in multipath
fading environments, the design of a new time-efficient
decoding algorithm, and a new interleaver design.
Initially, the performance of the DF decoder is
assessed in unfaded as well as Rayleigh fading multipath
propagation in additive white Gaussian noise interference.
Simulation results using coherent and noncoherent
detection are presented for both independent Rayleigh
fading and Rayleigh fading with a commonly used Doppler
spectrum. The results show improved performance compared
to conventional non-DF receivers using the same decoding
metric. This is a prerequisite for application of the DF
decoder in an actual mobile communications environment.
The effectiveness of the initial DF decoder design, as
it is applied to IS-95 based systems, is studied. It is
found that the effectiveness of the DF decoder is
determined by the decoding delay of the convolutional
decoder and the interleaver specification. Based on these
findings, two methodologies to improve the effectiveness
of the DF decoder are investigated. First, the average
decoding delay is reduced using sub-optimal convolutional
decoding. Second, the combination of a new block
interleaver design and the DF decoder is considered.
Simulation results of average decoding delay, bit error
rate and frame error rate are presented for coherent and
noncoherent detection of unfaded and Rayleigh fading
multipath signals. It is shown that both approaches result
in better system performance, which can further improve
the quality of service and/or capacity of an IS-95 based
system.
Finally, a simplified analysis of the DF decoder
performance is presented. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33359 |
| Date | 07 May 1999 |
| Creators | Volz, Patrick U. |
| Contributors | Magana, Mario E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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