  The peeling decoding for spatially coupled low-density parity-check (SC-LDPC)
codes is analyzed for a binary erasure channel. An analytical calculation of
the mean evolution of degree-one check nodes of protograph-based SC-LDPC codes
is given and an estimate for the covariance evolution of degree-one check nodes
is proposed in the stable decoding phase where the decoding wave propagates
along the chain of coupled codes. Both results are verified numerically.
Protograph-based SC-LDPC codes turn out to have a more robust behavior than
unstructured random SC-LDPC codes. Using the analytically calculated
parameters, the finite- length scaling laws for these constructions are given
and verified by numerical simulations.
