Patent ID: 8375278

Claim:
A method of porting k input bits, comprising: (a) encoding the input bits according to a first code with which is associated a parity check matrix H that has m rows and n=m+k columns, thereby producing a codeword of n bits; (b) puncturing the codeword, thereby providing a punctured codeword of n′<n bits; (c) exporting the punctured codeword to a corrupting medium; (d) importing a representation of the punctured codeword from the corrupting medium; (e) deriving, by merging selected rows of H, a matrix H′ that has m′=m−(n−n′) rows and n′ columns, wherein merging selected rows of H is terminated when further merging of the selected rows would produce a matrix H′ that fails to satisfy a predetermined criterion of sparseness; and (f) using H′ to decode the representation of the punctured codeword.