  Semi-definite relaxation (SDR) detector has been demonstrated to be
successful in approaching maximum likelihood (ML) performance while the time
complexity is only polynomial. We propose a new receiver jointly utilizing the
forward error correction (FEC) code information in the SDR detection process.
Strengthened by the code constraints, the joint SDR detector provides soft
information of much improved reliability to downstream decoder and therefore
outperforms existing receivers with substantial gain.
