Nguyen Dang, Thanh
Fountain codes for the wireless Internet.
University of Southampton, School of Electronics and Computer Science,
In this thesis, novel Foutain codes are proposed for transmission over wireless channels. The thesis concentrates on a specific version of Fountain codes, namely on Luby
transform codes. More specifically, we consider their concatenation with classic error correction codes, yielding schemes, such as the concatenated Luby Transform and Bit Interleaved Coded Modulation using Iterative Decoding (LT-BICM-ID), the amalgamated Luby Transform and Generalized Low Density Parity Check (LT-GLDPC) code, or the Luby Transform coded Spatial Division Multiple Access (LT-SDMA) scenario considered. The thesis also investigates the potential of Systematic Luby Transform (SLT) codes using
soft-bit decoding and analyses their Bit Error Ratio (BER) performance using EXtrinsic Information Transfer (EXIT) charts. SLT codes using different degree distributions and
random integer packet index generation algorithms for creating the parity and information part of the SLT codeword are also investigated in this thesis. For the sake of improving
both the BER performance and the diversity gain of Vertical Bell Laboratories Layered Space Time (V-BLAST) schemes, in this thesis a SLT coded V-BLAST system having four transmit and four receive antennas is proposed. Finally, A Hybrid Automatic Repeat reQuest (H-ARQ) SLT coded modulation scheme is designed in this thesis, where SLT codes are used both for correcting erroneous bits and for detecting as well as retransmitting erroneous Internet Protocol (IP) based packets. Erroneous IP packet detection is implemented using syndrome checking with the aid of the SLT codes’ Parity Check Matrix
(PCM). Optimizing the mapping of SLT-encoded bits to modulated symbols and then using iterative decoding for exchanging extrinsic information between the SLT decoder and
the demapper substantially improves the achievable Bit Error Ratio (BER) performance of the scheme.
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