Products of Random Matrices in Iterative (Turbo) Decoding

Conference: TURBO - CODING - 2006 - 4th International Symposium on Turbo Codes & Related Topics; 6th International ITG-Conference on Source and Channel Coding
04/03/2006 - 04/07/2006 at Munich, Germany

Proceedings: TURBO - CODING - 2006

Pages: 6Language: englishTyp: PDF

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Schmitt, Lars; Meyr, Heinrich (Institute for Integrated Signal Processing Systems ISS, RWTH Aachen University, Germany)

From an implementation as well as theoretical point of view it is a fundamental property of the symbol-by-symbol MAP decoding algorithm, that the dependence of the decoder output on the decoder inputs decays with distance in the code trellis. By using results from the theory of products of random matrices we present a general prove of this property and show that the rate of decay is exponentially with distance along the trellis. Furthermore, we examine how the rate of decay depends on the channel parameter and the a priori information, and how it evolves during the iterative decoding process. Finally, we comment on possible practical implications.