Classification of Unique Mappings for 8PSK Based on Bit-Wise Distance Spectra
2009 (English)In: IEEE Transactions on Information Theory, ISSN 0018-9448, Vol. 55, no 3, 1131-1145 p.Article in journal (Refereed) Published
The performance of bit-interleaved coded modulation (BICM) with (or without) iterative decoding (ID) is significantly influenced by the mapping of bits to the symbol constellation. Our main objective in this paper is to develop a systematic design approach for BICM-ID schemes, ensuring the best possible performance with iterative decoding. Although useful mappings for BICM-ID have been found based on various search strategies, no attempt has been made to systematically enumerate and classify all unique mappers for a given constellation. As the basis for a systematic enumeration and classification, we define the average bit-wise distance spectrum for a mapping from bits to symbols. Different bit-wise distance spectra are derived assuming no prior information or full prior information, respectively. The bit-wise distance spectra determine correspondingbit-wise error probability and bit-wise mutual information. The latter allows us to use theclassification of mappings with unique bit-wise distance spectra to also classifymappings with unique extremal points in the corresponding extrinsic information transfer (EXIT) curves. As an example of our approach, we classify 8PSK mappings into 86 classes of unique mappings according to bit-wise distance spectra. The classificationcan be used to significantly reduce the complexity of the search for suitable mappers for BICM-ID. For 8PSK and a given encoder, only 86 different mappings need to be investigated. As examples of the systematic design approach, the best 8PSK mappingsfor minimizing the convergence threshold are found for concatenation with the rate 1/2 (5, 7)8 and (133,1718 convolutional codes, and the rate 1/2 UMTS turbo code with identical constituent convolutional codes (15/13)8.
Place, publisher, year, edition, pages
2009. Vol. 55, no 3, 1131-1145 p.
8PSK mappings, Bit-interleaved coded modulation, Bit-wise distance spectrum, Error probability, EXIT chart, Mutual information
IdentifiersURN: urn:nbn:se:kth:diva-62612DOI: 10.1109/TIT.2008.2011506ISI: 000263928600017ScopusID: 2-s2.0-62749124839OAI: oai:DiVA.org:kth-62612DiVA: diva2:480798
QC 201202162012-01-192012-01-192012-02-16Bibliographically approved