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  • Research Article
  • Open Access

A Systematic Approach to Modified BCJR MAP Algorithms for Convolutional Codes

EURASIP Journal on Advances in Signal Processing20062006:095360

  • Received: 19 November 2004
  • Accepted: 12 September 2005
  • Published:


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.


  • Information Technology
  • Detailed Analysis
  • Computer Simulation
  • Markov Chain
  • Computational Complexity

Authors’ Affiliations

Defence Research and Development Canada *#8211; Ottawa, Ottawa, ON, K1A 0Z4, Canada
Communications Research Centre Canada, Ottawa, ON, K2H 8S2, 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.