As it is shown in Fig. 4(a), there exists many cycles in 2-D ISI channel factor graph in contrast to the sparse graphs of LDPC codes. As a result, the tree-like assumption used in BP does not hold and BP approximation is poor
As it is shown in Fig. 4(a), there existsmany cycles in 2-D ISI channel factor graph in contrast tothe sparse graphs of LDPC codes. As a result, the tree-likeassumption used in BP does not hold and BP approximationis poor