In this thesis, a combined subband coded image coding and 16-QAM scheme is considered. No error correcting codes are employed. Source bit streams which are divided into two groups by their significance are adaptively unequally protected in 16-QAM modulation block by the variable power assignment. Further, a new system which involves this 16-QAM scheme in the CDMA system is proposed. For this scheme, the analytic expressions for BER's of each group are derived for AWGN and Rayleigh fading channel environments. We treat the transmission of a still image and set up PSNR as the performance measure. For two source rates of 2.5 bpp and 1.5 bpp, the simulation results are presented for AWGN and Rayleigh fading channel environments and from these results, the optimal assignments of source bits and powers to each group are examined.
