The vision of anytime, anywhere communications coupled by the rapid growth of
wireless subscribers and increased volumes of internet users, suggests that the
widespread demand for always-on access data, is sure to be a major driver for the
wireless industry in the years to come. Among many cutting edge wireless
technologies, a new class of transmission techniques, known as Multiple-Input
Multiple-Output (MIMO) techniques, has emerged as an important technology
leading to promising link capacity gains of several fold increase in data rates and
spectral efficiency. While the use of MIMO techniques in the third generation (3G)
standards is minimal, it is anticipated that these technologies will play an important
role in the physical layer of fixed and fourth generation (4G) wireless systems.
Concatenated codes, a class of forward error correction codes, of which Turbo codes
are a classical example, have been shown to achieve reliable performance which
approach the Shannon limit. An effective and practical way to approach the capacity
of MIMO wireless channels is to employ space-time coding (STC). Space-Time
coding is based on introducing joint correlation in transmitted signals in both the
space and time domains. Space-Time Trellis Codes (STTCs) have been shown to
provide the best trade-off in terms of coding gain advantage, improved data rates and
computational complexity.
Super-Orthogonal Space-Time Trellis Coding (SOSTTC) is the recently proposed
form of space-time trellis coding which outperforms its predecessor. The code has a
systematic design method to maximize the coding gain for a given rate, constellation
size, and number of states. Simulation and analytical results are provided to justify the
improved performance. The main focus of this dissertation is on STTCs, SOSTTCs
and their concatenated versions in quasi-static and rapid Rayleigh fading channels.
Turbo codes and space-time codes have made significant impact in terms of the
theory and practice by closing the gap on the Shannon limit and the large capacity gains provided by the MIMO channel, respectively. However, a convincing solution
to exploit the capabilities provided by a MIMO channel would be to build the turbo
processing principle into the design of MIMO architectures. The field of concatenated
STTCs has already received much attention and has shown improved performance
over conventional STTCs. Recently simple and double concatenated STTCs
structures have shown to provide a further improvement performance. Motivated by
this fact, two concatenated SOSTTC structures are proposed called Super-orthogonal
space-time turbo codes. The performance of these new concatenated SOSTTC is
compared with that of concatenated STTCs and conventional SOSTTCs with
simulations in Rayleigh fading channels. It is seen that the SOST-CC system
outperforms the ST-CC system in rapid fading channels, whereas it maintains
performance similar to that in quasi-static. The SOST-SC system has improved
performance for larger frame lengths and overall maintains similar performance with
ST-SC systems. A further investigation of these codes with channel estimation errors
is also provided. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2005.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/4312 |
| Date | January 2005 |
| Creators | Pillai, Jayesh Narayana. |
| Contributors | Mneney, Stanley H. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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