(mar 1997, student project) Bibliographic study, implementation, optimization and simulation of the soft decoding of some linear error correcting codes (ECC). This study was especially focused on the soft decoding of the parity extended BCH(32,31) code used by the ERMES paging standard. An original point was to show how to soft-decode random linear ECCs. This study was initiated by JC Belfiore . You can get the postscript report in French. The source code of the generic simulation engine is available uppon request.