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Báo cáo hóa học: " Research Article Error Recovery Properties and Soft Decoding of Quasi-Arithmetic Codes"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Error Recovery Properties and Soft Decoding of Quasi-Arithmetic Codes | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 752840 12 pages doi 10.1155 2008 752840 Research Article Error Recovery Properties and Soft Decoding of Quasi-Arithmetic Codes Simon Malinowski 1 Herve Jegou 1 and Christine Guillemot2 1 IRISA University of Rennes Campus de Beaulieu 35042 Rennes Cedex France 2IRISA INRIA Campus de Beaulieu 35042 Rennes Cedex France Correspondence should be addressed to Simon Malinowski simon.malinowski@irisa.fr Received 4 October 2006 Revised 19 March 2007 Accepted 9 July 2007 Recommended by Joerg Kliewer This paper first introduces a new set of aggregated state models for soft-input decoding of quasi arithmetic QA codes with a termination constraint. The decoding complexity with these models is linear with the sequence length. The aggregation parameter controls the tradeoff between decoding performance and complexity. It is shown that close-to-optimal decoding performance can be obtained with low values of the aggregation parameter that is with a complexity which is significantly reduced with respect to optimal QA bit symbol models. The choice of the aggregation parameter depends on the synchronization recovery properties of the QA codes. This paper thus describes a method to estimate the probability mass function PMF of the gain loss of symbols following a single bit error i.e. of the difference between the number of encoded and decoded symbols . The entropy of the gain loss turns out to be the average amount of information conveyed by a length constraint on both the optimal and aggregated state models. This quantity allows us to choose the value of the aggregation parameter that will lead to close-to-optimal decoding performance. It is shown that the optimum position for the length constraint is not the last time instant of the decoding process. This observation leads to the introduction of a new technique for robust decoding of QA codes with redundancy which turns out to .