Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Low earth orbit (LEO) satellite communication presents a unique environment
which inherently di ers from most other communication channels.
Due to the varying orbital patterns of LEO satellites the link exhibits varying
link margins. Limited communication time windows need to be optimised to
maximise the volumetric data throughput.
Large coding gains can be obtained by the implementation of forward error
correction codes. This thesis presents a means for optimising the data
throughput of LEO satellite communication through the implementation of a
mission speci c error control strategy. Low density parity check (LDPC) codes
are versatile and present good error performances at many di erent code rates
and block lengths. With power limitations on the space segment and remote
ground stations, hardware utilisation e ciency must be optimised to reduce
power consumption. In response to this requirement, this thesis evaluates
various algorithms for LDPC decoders.
An iterative LDPC decoder, implementing an approximation algorithm,
is presented as a low complexity solution with good error performance. The
proposed solution provides a very good balance between required hardware
complexity and coding performance. It was found that many parameters of
the decoders and codes can be altered to allow the implementation of these
codes in systems with varying memory and processing capabilities. / AFRIKAANSE OPSOMMING: Kommunikasiekanale van satelliete met lae wentelbane, bied 'n unieke omgewing
wat inherent verskil van meeste ander kommunikasiekanale. As gevolg
van veranderende wentelbaanpatrone, vertoon die kanaal 'n wisselende foutgedrag.
Kommunikasievensters is beperk en moet geoptimeer word om die totale
deurset van die stelsel te maksimeer.
Groot koderingswinste kan verkry word deur die implementering van foutkorreksie
kodes. Hierdie tesis voorsien 'n metode om die datadeurset van
satelliete met lae wentelbaan te optimeer, deur middel van implementering
van 'n missie-spesi eke foutbeheer strategie. Lae digtheid pariteit toetskodes
(LDPC) is veelsydige kodes, bied goeie foutbeheer en is doeltre end vir verskillende
kodekoerse en bloklengtes. Met drywingsbeperkinge op die ruimtesegment
en afgesonderde grondstasies, moet hardeware komponente doeltreffend
gebruik word om drywingsverbruik te verminder. Ten einde aan hierdie
ontwerpsvereiste te voldoen, evalueer hierdie tesis verskeie LDPC dekodeerderalgoritmes.
Deur 'n iteratiewe LDPC dekodeerder met 'n benaderingsalgoritme te implementeer,
word 'n oplossing van lae kompleksiteit aangebied, maar wat steeds
goeie foutkorreksie eienskappe toon. Die voorgestelde oplossing bied 'n baie
goeie balans tussen benodigde hardeware kompleksiteit en koderingsprestasie.
Daar is gevind dat heelwat parameters van die dekodeerders en kodes aangepas
kan word, ten einde implementering in stelsels met 'n wye verskeidenheid van
geheuespasie en verwerkingsvermoëns moontlik te maak.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/1828 |
| Date | 12 1900 |
| Creators | Olivier, Francois Jacobus |
| Contributors | Wolhuter, R., University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | Unknown |
| Type | Thesis |
| Rights | University of Stellenbosch |
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