Optimal M-BCJR Turbo Decoding: The Z-MAP Algorithm

Aissa Ouardi, Ali Djebbari, Boubakar Seddik Bouazza

.

DOI: 10.4236/wet.2011.24031                

Abstract

In this paper, we propose a novel idea for improvement performances of the leader M-BCJR algorithm functioning in low complexity. The basic idea consists to localize error instant possibility, and then increase the complexity around this moment. We also propose an easy and important idea for early localisation of erroneous moments. We call this new algorithm Z-MAP. The simulations show that the improvement of performances is significant. The performances of Z-MAP turbo decoding are so close to full MAP-BCJR performances. Furthermore, the complexity is the same that of the M-BCJR. So, Z-MAP is an optimal version of M-BCJR algorithm.

Keywords

MAP-BCJR Algorithm, M-BCJR, Turbo Decoding, Complexity Reduction, Error Localisation Criterion

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	V. Franz and J. B. Anderson, “Concatenated Decoding with a Reduced-Search BCJR Algorithm,” IEEE Journal on Selected Areas in Communication, Vol. 16, No. 2, 1998, pp. 186-195.
[2]	L. R. Bahl, J. Cocke, F. Jelinek and R. Raviv, “Optimal Decoding of Linear Codes for Minimizing Symbol Error Rate”, IEEE Transactions on Information Theory, Vol. 20, No. 2, 1974, pp. 284-287. doi:10.1109/TIT.1974.1055186
[3]	G. Bauch, H. Khorram and J. Hagenauer, “Iterative Equalization and Decoding in Mobile Communications Systems,” Proceedings of the 2nd European Personal Mobile Communications Conference, 1997, pp. 307-312.
[4]	J. B. Anderson and A. Prlja, “Turbo Equalization and an M-BCJR Algorithm for Strongly Narrowband Intersymbol Interference,” 2010 International Symposium on Information Theory and its Applications (ISITA), Taichung, 2010, pp. 261-266.
[5]	C. Fragouli, N. Seshadri and W. Turin, “On the Reduced Trellis Equalization Using the M-BCJR Algorithm,” IEEE Annual Conference on Information Sciences and Systems (CISS 2000), Boston, 2000, pp. 28-33.
[6]	P. Kumar, R. M. Banakar and B. Shankaranand, “M- BCJR Based Turbo Equalizer,” Proceedings of the Conference on Information Technology, 2004, pp. 376-386.
[7]	K. R. Narayanan, R. V. Tamma, E. Kurtas and X. Yang, “Performance Limits of Turbo Equalization Using M-BCJR Algorithm,” Proceedings of the 3rd International Symposium on Turbo Codes, 2003, pp. 2031-2035.
[8]	O. Aissa, A. Djebbari and B. S. Bouazza, “Partial Turbo Detection with Reduced Complexity,” International Jour- nal of Electronics, Vol. 98, No. 6, 2011, pp. 825-831. doi:10.1080/00207217.2011.567040
[9]	C. Berrou, A. Glavieux and P. Thitimajshima, “Near Shannon Limit Error-Correcting and Decoding: Turbo-Codes (1),” IEEE International Conference on Communications, Vol. 2, 1993, pp. 1064-1070.