Jointly Decoded Raptor Codes: Analysis and Design for the BIAWGN Channel. (19th July 2009)

• Record Type: Journal Article
• Authors: Venkiah, Auguste; Poulliat, Charly; Declercq, David
• Other Names: Le-Ngoc Tho Academic Editor.
• Is Part Of: EURASIP journal on wireless communications and networking. Volume 2009(2009)
• Publication Date: 2009-07-19
• Subjects: Wireless communication systems -- Periodicals; Signal processing -- Periodicals; 621.38405
• DOI: 10.1155/2009/657970
• Languages: English
• ISSNs: 1687-1499

Abstract

Abstract : We are interested in the analysis and optimization of Raptor codes under a joint decoding framework, that is, when the precode and the fountain code exchange soft information iteratively. We develop an analytical asymptotic convergence analysis of the joint decoder, derive an optimization method for the design of efficient output degree distributions, and show that the new optimized distributions outperform the existing ones, both at long and moderate lengths. We also show that jointly decoded Raptor codes are robust to channel variation: they perform reasonably well over a wide range of channel capacities. This robustness property was already known for the erasure channel but not for the Gaussian channel. Finally, we discuss some finite length code design issues. Contrary to what is commonly believed, we show by simulations that using a relatively low rate for the precode( R p ≃ 0.9 ), we can improve greatly the error floor performance of the Raptor code.