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Super-orthogonal space-time turbo coded OFDM systems.

The ever increasing demand for fast and efficient broadband wireless communication

services requires future broadband communication systems to provide a high data rate,

robust performance and low complexity within the limited available electromagnetic

spectrum. One of the identified, most-promising techniques to support high

performance and high data rate communication for future wireless broadband services

is the deployment of multi-input multi-output (MIMO) antenna systems with

orthogonal frequency division multiplexing (OFDM). The combination of MIMO and

OFDM techniques guarantees a much more reliable and robust transmission over a

hostile wireless channel through coding over the space, time and frequency domains.

In this thesis, two full-rate space-time coded OFDM systems are proposed. The first

one, designed for two transmit antennas, is called extended super-orthogonal space-time

trellis coded OFDM (ESOSTTC-OFDM), and is based on constellation rotation. The

second one, called super-quasi-orthogonal space-time trellis coded OFDM (SQOSTTCOFDM),

combines a quasi-orthogonal space-time block code with a trellis code to

provide a full-rate code for four transmit antennas. The designed space-time coded

MIMO-OFDM systems achieve a high diversity order with high coding gain by

exploiting the diversity advantage of frequency-selective fading channels.

Concatenated codes have been shown to be an effective technique of achieving reliable

communication close to the Shannon limit, provided that there is sufficient available

diversity. In a bid to improve the performance of the super orthogonal space-time

trellis code (SOSTTC) in frequency selective fading channels, five distinct

concatenated codes are proposed for MIMO-OFDM over frequency-selective fading

channels in the second part of this thesis. Four of the coding schemes are based on the

concatenation of convolutional coding, interleaving, and space-time coding, along

multiple-transmitter diversity systems, while the fifth coding scheme is based on the

concatenation of two space-time codes and interleaving. The proposed concatenated

Super-Orthogonal Space-Time Turbo-Coded OFDM System I. B. Oluwafemi 2012 vii

coding schemes in MIMO-OFDM systems achieve high diversity gain by exploiting

available diversity resources of frequency-selective fading channels and achieve a high

coding gain through concatenations by employing the turbo principle. Using computer

software simulations, the performance of the concatenated SOSTTC-OFDM schemes is

compared with those of concatenated space-time trellis codes and those of conventional

SOSTTC-OFDM schemes in frequency-selective fading channels. Simulation results

show that the concatenated SOSTTC-OFDM system outperformed the concatenated

space-time trellis codes and the conventional SOSTTC-OFDM system under the

various channel scenarios in terms of both diversity order and coding gain. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2012.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/8505
Date January 2012
CreatorsOluwafemi, Ilesanmi Banjo.
ContributorsMneney, Stanley H.
Source SetsSouth African National ETD Portal
Languageen_ZA
Detected LanguageEnglish
TypeThesis

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