Open Access

A Systematic Approach to Modified BCJR MAP Algorithms for Convolutional Codes

EURASIP Journal on Advances in Signal Processing20062006:095360

DOI: 10.1155/ASP/2006/95360

Received: 19 November 2004

Accepted: 12 September 2005

Published: 13 April 2006


Since Berrou, Glavieux and Thitimajshima published their landmark paper in 1993, different modified BCJR MAP algorithms have appeared in the literature. The existence of a relatively large number of similar but different modified BCJR MAP algorithms, derived using the Markov chain properties of convolutional codes, naturally leads to the following questions. What is the relationship among the different modified BCJR MAP algorithms? What are their relative performance, computational complexities, and memory requirements? In this paper, we answer these questions. We derive systematically four major modified BCJR MAP algorithms from the BCJR MAP algorithm using simple mathematical transformations. The connections between the original and the four modified BCJR MAP algorithms are established. A detailed analysis of the different modified BCJR MAP algorithms shows that they have identical computational complexities and memory requirements. Computer simulations demonstrate that the four modified BCJR MAP algorithms all have identical performance to the BCJR MAP algorithm.


Authors’ Affiliations

Defence Research and Development Canada *#8211; Ottawa
Communications Research Centre Canada


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© S. Wang and F. Patenaude. 2006

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.