Patent ID: 8433972

Claim:
A system for constructing a quasi-cyclic (QC)-low density parity check code (LDPC) base matrix for encoding information bits comprising: a design module configured to construct the QC-LDPC base matrix based on predetermined design constraints including a local girth constraint for variable nodes imposed for at least one lift size, wherein the LDPC is constructed by copying a protograph z times and permuting the z edges (lifting) and z corresponds to a lift size; and an evaluation module configured to compute and provide the local girth of variable nodes in the QC-LDPC matrix to permit the design module to determine whether variable nodes in the QC-LDPC base matrix satisfy the local girth constraint for a corresponding lift size, wherein the design constraints further include a local minimum approximate cycle extrinsic message degree (ACE) constraint for variable nodes in the QC-LDPC base matrix.