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Báo cáo hóa học: " Joint Source-Channel Decoding of Variable-Length Codes with Soft Information: A Survey"

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: Joint Source-Channel Decoding of Variable-Length Codes with Soft Information: A Survey | EURASIP Journal on Applied Signal Processing 2005 6 906-927 2005 Hindawi Publishing Corporation Joint Source-Channel Decoding of Variable-Length Codes with Soft Information A Survey Christine Guillemot IRISA-INRIA Campus de Beaulieu 35042 Rennes Cedex France Email christine.guillemot@irisa.fr Pierre Siohan R D Division France Telecom 35512 Rennes Cedex France Email pierre.siohan@francetelecom.com Received 13 October 2003 Revised 27 August 2004 Multimedia transmission over time-varying wireless channels presents a number of challenges beyond existing capabilities conceived so far for third-generation networks. Efficient quality-of-service QoS provisioning for multimedia on these channels may in particular require a loosening and a rethinking of the layer separation principle. In that context joint source-channel decoding JSCD strategies have gained attention as viable alternatives to separate decoding of source and channel codes. A statistical framework based on hidden Markov models HMMs capturing dependencies between the source and channel coding components sets the foundation for optimal design of techniques of joint decoding of source and channel codes. The problem has been largely addressed in the research community by considering both fixed-length codes FLC and variable-length source codes VLC widely used in compression standards. Joint source-channel decoding of VLC raises specific difficulties due to the fact that the segmentation of the received bitstream into source symbols is random. This paper makes a survey of recent theoretical and practical advances in the area of JSCD with soft information of VLC-encoded sources. It first describes the main paths followed for designing efficient estimators for VLC-encoded sources the key component of the JSCD iterative structure. It then presents the main issues involved in the application of the turbo principle to JSCD of VLC-encoded sources as well as the main approaches to source-controlled channel decoding. This .