Enhanced coding for informed decoders

Abstract

The invention relates to method of encoding address words (a) comprising address symbols (a, a, . . . a) into codewords (c) of a code (C) for providing an enhanced error correction capability if at least one information symbol (m) of information words (m) is known a priori to a decoder decoding received, possibly mutilated codewords (r). The invention relates further to a method of decoding possibly mutilated codewords (r). In order to design a code of which the correction power is enhanced if some information symbols are known to the decoder prior to decoding it is proposed according to the invention that the address words (a) are encoded into information words (m) such that that address words comprising addresses being close to each other share a plurality of information symbols and that said information words (m) are encoded into codewords (c) using a generator matrix (G) which is selected such that the minimum Hamming distance of at least one subcode (C') of said code (C) is larger than the minimum Hamming distance of said code (C) and that a subcode generator matrix (G′) of said subcode (C′) derives from said generator matrix (G) of said code (C) by omitting the at least one row from said generator matrix (G) corresponding to said at least one a priori known information symbol (m).