Summary: IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. 50, NO. 11, NOVEMBER 2004 2657
Extrinsic Information Transfer Functions:
Model and Erasure Channel Properties
Alexei Ashikhmin, Member, IEEE, Gerhard Kramer, Member, IEEE, and Stephan ten Brink, Member, IEEE
Abstract--Extrinsic information transfer (EXIT) charts are
a tool for predicting the convergence behavior of iterative pro-
cessors for a variety of communication problems. A model is
introduced that applies to decoding problems, including the
iterative decoding of parallel concatenated (turbo) codes, serially
concatenated codes, low-density parity-check (LDPC) codes, and
repeat­accumulate (RA) codes. EXIT functions are defined using
the model, and several properties of such functions are proved for
erasure channels. One property expresses the area under an EXIT
function in terms of a conditional entropy. A useful consequence
of this result is that the design of capacity-approaching codes
reduces to a curve-fitting problem for all the aforementioned
codes. A second property relates the EXIT function of a code
to its Helleseth­Kløve­Levenshtein information functions, and
thereby to the support weights of its subcodes. The relation is
via a refinement of information functions called split information

Source: Ashikhmin, Alexei - Enabling Computing Technologies, Bell Laboratories
Kramer, Gerhard - Department of Electrical Engineering, University of Southern California
Kramer, Gerhard - Mathematics of Communications, Mathematical Sciences Research Center, Bell Laboratories

Collections: Computer Technologies and Information Sciences; Engineering; Mathematics