EXIT ChartAnalysisof Binary
Gottfried Lechner, Troels Pedersen, Frederik Bajers Vej, Gerhard G. Kramer · 2007
Binary message-passing decoders forLDPC codes areanalyzed using EXITcharts. Fortheanalysis, thevariable nodedecoder performs allcomputations intheL-value domain. Forthespecial caseofa harddecision channel, thisleadsto thewell-know Gallager B algorithm, whiletheanalysis canbe extended tochannels withlarger output alphabets. Byincreasing theoutput alphabet fromharddecisions tofoursymbols, again ofmorethan1.0dBisachieved using optimized codes. Forthis codeoptimization, themixing property ofEXITfunctions hasto bemodified tothecaseofbinary message-passing decoders.