TRELLIS-CODED 16-QAM FOR FADING CHANNELS

Fast growth in digital communications leads to increasing needs for hi gh data transmission rates. Such needs can be met by bandwidth efficie nt modulation schemes. In this paper, a trellis coded 16-QAM scheme ov er flat fading channels is considered. Through analysis, new bounds on error rate performance of the scheme are derived. A set of new criter ia for code design based on these bounds are formulated and used to co nstruct new trellis 16-QAM codes for fading channels. One of the key p arameters in code design is the minimum product distance. An algorithm for computing the minimum product distance and its multiplicity is pr oposed. The algorithm is applied in search for optimum trellis codes. The performance of 16-QAM TCM schemes with ideal channel state informa tion (CSI) on Rayleigh fading channels is evaluated by simulation. The results show the proposed codes achieve significant improvements rela tive to the best known 16-QAM modulation codes as well as 16-PSK codes .