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Title: Iterative decoding of multilevel and bit-interleaved coded modulation
Author: Tee, Ronald Yee Siong
ISNI:       0000 0001 3515 6708
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2008
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A comparative study of various codeq. modulation schemes is carried out in terms of their different block length, number of iterations and complexity, quantified by the number of trellis states as well as the EXtrinsic Information Transfer (EXIT) charts are used for analysing their decoding convergence and Bit Error Ratio (BER). A threeDimensional (3-D) EXIT chart is introduced for MultiLevel Coding (MLC) invoking MultiStage Decoding (MSD). Based on this 3-D EXIT chart, we design a precodedMLC scheme employing both MSD and Parallel Independent Decoding (PID). In order to provide space diversity, we study the new arrangement of Bit-Interleaved Coded Modulation with Iterative Decoding (BICM-ID) and MLC combined with Space Time Block Codes (STBC) invoking a novel Sphere Packing (SP) modulation scheme. An equivalent-capacIty-based design of MLCs based on this SP modulation is proposed. We use the Binary Switching Algorithm (BSA) to optimise our cost function for the sake of obtaining appropriate bit-to-SP-symbol mapping schemes. A hybrid mapping scheme is introduced for achieving unequal error protection. Furthermore, bit-to-SP-symbol mapping to 256 constellation points is designed for a serially concatenated BICM-ID aided twin-antenna STBC arrangement for creating a system, which is capable of outperforming an identical-throughput 16-level Quadrature Amplitude Modulation (16QAM) scheme. Furthermore, the benefits of MLC PID designs employing Generalised Low Density Parity Check (GLDPC) codes are investigated, which results in a low-delay scheme useful for multimedia transmission. A stopping criterion is designed for this scheme for the sake of terminating the iterative decoding process, once the target BER is attained. We then contrive coding schemes for the wireless Internet by introducing a BICM-ID scheme combined with Luby Transform (LT) coding constructed for the AWGN-contaminated Binary Erasure Channel (BEC). An improved robust LT packetdegree distribution is introduced for determining the specific number of LT source packets combined with modulo-2 additions in order to create an LT-encoded packet. Furthermore, a Log-Likelihood Ratio (LLR) based reliability estimation scheme is invoked in order to achieve a performance improvement based on this amalgamated design. Finally, a near-capacity Irregular Bit-Interleaved Coded Modulation with Iterative Decoding (Ir-BICM-ID) scheme was designed with the aid of an EXIT chart. An Irregular Convolution Code (IrCC) is proposed for the sake of introducing a diverse range of outer code EXIT functions. By contrast, the inner code is based on the serially concatenated components constituted by an Irregular Unity-Rate Code (IrURC) and an Irregular Mapper (IrMapper). An EXIT chart matching algorithm is invoked for constructing an Ir-BICM-ID scheme, which exhibits a narrow but still open EXIT tunnel and hence approaches the theoretical capacity limit.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available