Patent ID: 7685497

Claim:
In an encoder for a rate K/N, periodic LDPC code, where N, the number of bits in a codeword, equals the sum of K, the number of information bits, and T, the number of parity bits, the code characterized by a Table, each row of which represents M columns of a Parity Check Matrix for the code, the Parity Check Matrix defining participating bit nodes for each check node in a node representation of the code, where a row in the Table, if successively modulo-T shifted by q, where q equals T/M, generates a corresponding M columns of the Parity Check Matrix, a method of encoding K information bits, comprising the following steps: providing at least one Inverse Table of reduced form in relation to the Parity Check Matrix and identifying, for each of q check nodes, at least one participating bit node; for a check node p, using the at least one Inverse Table to identify at least one participating bit node for a check node v, where v=p mod q; and using the identified at least one participating bit node for the check node v to encode the K information bits, resulting in T parity bits that can be associated with the K information bits to form a codeword.