Starting from a finite projective plane, a simple construction of low-density parity check (LDPC) matrices is presented. The factor graphs associated with these LDPC matrices have no 4-cycles due to the incident structure of lines and points in the projective plane. Furthermore, two constructions are proposed to combine suitably sized smaller LDPC matrices into a larger LDPC matrix. These constructions can be used to obtain infinite sequences of Steiner systems of any block size, which are
2-designs.
Index terms: Finite geometries, Steiner systems, low-density parity-check (LDPC) codes
By: T. Mittelholzer
Published in: RZ3299 in 2000
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