ML Performances of Serial Turbo Codes do not Concentrate!
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
Personal VDE Members are entitled to a 10% discount on this title
Authors:
Como, Giacomo; Garin, Federica; Fagnani, Fabio (Dipartimento di Matematica, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy)
Abstract:
In this paper we investigate the typical behaviour of minimum distance and ML word error probability of a serial turbo concatenation with random interleaver, when the interleaver length N goes to infinity. Our main result shows that the word error probability P(e) goes to zero subexponentially in N with probability one. While it is known that log E[P(e)]/ logN converges to a constant, we prove that with probability one the sequence log(-log(P(e)))/ log N approaches an interval [α, β] C (0, 1), thus showing that the expected error rate is dominated by an asymptotically negligible fraction of bad interleavers. Our analysis is based on precise estimations of the minimum distance distribution.