tailieunhanh - Báo cáo hóa học: " Iterative Source-Channel Decoding: Improved System Design Using EXIT Charts"

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: Iterative Source-Channel Decoding: Improved System Design Using EXIT Charts | EURASIP Journal on Applied Signal Processing 2005 6 928-941 2005 M. Adrat and P. Vary Iterative Source-Channel Decoding Improved System Design Using EXIT Charts Marc Adrat Institute of Communication Systems and Data Processing Aachen University of Technology RWTH 52056 Aachen Germany Email adrat@ Peter Vary Institute of Communication Systems and Data Processing Aachen University of Technology RWTH 52056 Aachen Germany Email vary@ Received 1 October 2003 Revised 5 April 2004 The error robustness of digital communication systems using source and channel coding can be improved by iterative sourcechannel decoding ISCD . The turbo-like evaluation of natural residual source redundancy and of artificial channel coding redundancy makes step-wise quality gains possible by several iterations. The maximum number of profitable iterations is predictable by an EXIT chart analysis. In this contribution we exploit the EXIT chart representation to improve the error correcting concealing capabilities of ISCD schemes. We propose new design guidelines to select appropriate bit mappings and to design the channel coding component. A parametric source coding scheme with some residual redundancy is assumed. Applying both innovations the new EXIT-optimized index assignment as well as the appropriately designed recursive nonsystematic convolutional RNSC code allow to outperform known approaches to ISCD by far in the most relevant channel conditions. Keywords and phrases iterative source-channel decoding turbo principle soft-input soft-output decoding softbit source decoding extrinsic information EXIT charts. 1. INTRODUCTION The design and development guidelines for today s digital communication systems are inspired by the information theoretic considerations of C. E. Shannon. His fundamental statements indicate that in order to find the most error resistant realization of a communication system the transmit respectively receive operations are in principle