Figure 6
From: Analysis and Construction of Full-Diversity Joint Network-LDPC Codes for Cooperative Communications
Two special rootchecks for punctured bits (shaded bit nodes). (a) is a second-order rootcheck. Imagine that all blue bits are erased, than the shaded bit node will be retrieved in the second iteration. (b) represents two rootchecks where both rootchecks have leaves with other colors. Imagine that one color has been erased, than the shaded bit node will still be recovered after the first iteration.