  We propose a new family of spatially coupled product codes, called sub-block
rearranged staircase (SR-staircase) codes. Each SR-staircase code block is
constructed by encoding rearranged preceding code blocks and new information
blocks, where the rearrangement involves sub-blocks decomposition and
transposition. The proposed codes can be constructed to have each code block
size of $1/q$ to that of the conventional staircase codes while having the same
rate and component codes, for any positive integer $q$. In this regard, we can
use strong algebraic component codes to construct SR-staircase codes with a
similar or the same code block size and rate as staircase codes with weak
component codes. Moreover, both waterfall and error floor performance can be
further improved by using a large coupling width. The superior performance of
the proposed codes is demonstrated through density evolution and error floor
analysis as well as simulation.
