Looking for info about the MAP and BCJR algorithms

Hey,
For the purpose of Turbo decoder, i need some links and PDF , ieee papers dealing with maximum a-posterior(MAP) algorithm ,BCJR algorithm.. I need the basics of these topics.. Can anyone help pl...

Thanks in advance,

Venkatesan.s

Re: INFO about MAP?

Hi,

venkat3271 said:

Hey,
For the purpose of Turbo decoder, i need some links and PDF , ieee papers dealing with maximum a-posterior(MAP) algorithm ,BCJR algorithm.. I need the basics of these topics.. Can anyone help pl...

Thanks in advance,

Venkatesan.s

Click to expand...

The BCJR algorithm is named in the honour of its four originators: Bahl, Jelinek, and Raviv who coauthored the first forward-backward method for implementing maximum a posterior probability decoding in 1974.

As the MAP algorithm includes forward-backward recursion so it is also referred as the BCJR algorithm in recoginition of its originators. In simple words, MAP algorithm involves a double recursion, consequently it has at least twice the complexity of the Viterbi algorithm in itsmost general form. However, it produces soft outputs,a feature that is the key to its usefulness in the turbo decoding algorithm[1].

For further information see the reference below.

[1]: For the MAP algorithm, see the book "Modern Wireless Communications" by S. Haykin and M. Moher, chapter 4, page 219 to 222. The complete description and implementation of the MAP algorithm is in these 3 pages.

BR,

MAK,

Plz dont forget to press helped me!!!

Added after 3 minutes:

Hi,

sorry i forget to put the name of Cocke while mentioning the authors of BCJR algorithm. Please include this as well.

INFO about MAP?

Read this book :
Digital Communications , 4th ed, by John Proakis

Re: INFO about MAP?

Hi,

You can find the MAP algorithm explained in "Digital communications Fundamentals and application" - by Sklar. It is really avery good explaination.

Re: INFO about MAP?

You can see my example of MAP Turbo decoding that I have put on my website at
www.complextoreal.com/tutorial.htm

I am in the process of revising the material,

CL