The turbo decoding algorithm and its phase trajectories

Author

Agrawal, Dakshi ; Vardy, Alexander

Author_Institution

Coordinated Sci. Lab., Illinois Univ., Urbana, IL, USA

fYear

2000

fDate

2000

Firstpage

316

Abstract

We analyze phase trajectories of the turbo decoding algorithm as a function of the signal-to-noise ratio (SNR). We prove the existence of fixed points not only at asymptotically high SNRs but also at asymptotically low SNRs. Fixed points at practical SNRs are empirically divided into two classes: indecisive fixed points which usually lead to numerous erroneous decisions and unequivocal fixed points which usually correspond to correct decisions. The waterfall region in the performance curve of turbo decoding is characterized as the region of transition from convergence to indecisive fixed points to convergence to unequivocal fixed points

Keywords

AWGN channels; convergence of numerical methods; iterative decoding; phase shift keying; turbo codes; AWGN channels; BPSK modulation; SNR; convergence; correct decisions; erroneous decisions; fixed points existence; indecisive fixed points; performance curve; phase trajectories; signal-to-noise ratio; turbo decoding algorithm; unequivocal fixed points; waterfall region; Algorithm design and analysis; Convergence; Gaussian noise; Iterative algorithms; Iterative decoding; Modulation coding; Phase modulation; Signal analysis; Sufficient conditions; Turbo codes;

fLanguage

English

Publisher

ieee

Conference_Titel

Information Theory, 2000. Proceedings. IEEE International Symposium on

Conference_Location

Sorrento

Print_ISBN

0-7803-5857-0

Type

conf

DOI

10.1109/ISIT.2000.866614

Filename

866614