Abstract
This paper examines the log-likelihood addition aspects of the Turbo Decoding of product codes. Simple Parity Check (SPC) codes are used as the Constituent Codes (CCs) of the Turbo encoder in an array code format. The general approximation used in the log-likelihood addition of the soft values of the code bits is evaluated and some results are presented. Two iterative (“Turbo’) decoding algorithms for block codes are compared, only one of which uses the previously mentioned approximation. The first is set out in Hagenauer (1994), which uses the dual code method to implement the MAP decoder, and the second was developed in Pyndiah (1994), which uses an algorithm presented in Chase (1972). The results presented show the affect of the approximation on decoder performance. The outcome differs somewhat from that which was expected.
Preview
Unable to display preview. Download preview PDF.
References
Berrou, C., Glavieux, A., & Thitimajshima, P., “Near Shannon limit error correcting coding and decoding: Turbo Codes”, IEEE Int. Conf. on Comm.s, 1993, (ICC'93), Geneva, pp. 1064-1070, May 1993.
Forney Jr., G.D., “Concatenated Codes”, M.I.T., Cambridge, MA, USA, 1966.
Hagenauer, J., Robertson, P., & Papke, L., “Iterative ('Turbo') decoding of systematic convolutional codes with the MAP and SOVA algorithms”, ITG Conference, Munich, Germany, pp. 1–9, 26–28 Oct. 1994.
Hagenauer, J., “Iterative Decoding of Binary Block and Convolutional Codes”, IEEE Trans. on Information Theory, Vol.42(2), pp.429–445, March 1996.
Hoeher, P., “New Iterative (`Turbo') Decoding Algorithms”, Proceedings of International Symposium on Turbo Codes & Related Topics., Brest, France, pp.63–70, 3rd-5 th September 1997.
Mohammadi, A.H.S., & Khandani, A.K., “Unequal Error Protection on Turboencoder Output bits”, Electronic Letters, Vol.33(4), pp.273–274, 13th Feb. 1997.
Author information
Authors and Affiliations
Editor information
Rights and permissions
Copyright information
© 1997 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
McManus, S., Farrell, P. (1997). Evaluation of standard approximation to log-likelihood ratio addition in the MAP algorithm, and Its application in block code (‘Turbo’) Iterative decoding algorithms. In: Darnell, M. (eds) Crytography and Coding. Cryptography and Coding 1997. Lecture Notes in Computer Science, vol 1355. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0024469
Download citation
DOI: https://doi.org/10.1007/BFb0024469
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-63927-5
Online ISBN: 978-3-540-69668-1
eBook Packages: Springer Book Archive