Joint Source-Channel Coding and Digital Modulation Technique with Index Assignment Optimization

Abstract

Channel  optimized  Index  Assignment  (IA)  of source  codeword  is  an  approach  to  improve  the transmission error resilience  without the  addition of  extra bits  and  coding/decoding  complexity.  In  this  paper,  we study  the  IA  scheme  with  consideration  to  the  given modulation  technique.  This  study  also  presents  an  IA scheme  for  joint  source  channel  coding  and  modulation technique  for  the  general  case  when  the  codeword  is  not required  to  correspond  to  a  modulation  symbol  and  to occupy  consecutive  bits  of  the  transmitted  bitstream  as some  prior  works.  Besides  the  improvement  in  channel error  robustness  for  the  traditional  IA  approach,  the proposed scheme can be combined with other techniques of mitigating or controlling the channel error when needed (in systems  with  high  reliability  or  transmission  of  important codeword)  such  as  Cyclic  Redundancy  Check  (CRC), Forward Error Correction (FEC) coding and interleaving. We also consider the combination of  the IA approach and FEC coding and the effectiveness of the proposed scheme is confirmed by experiments.