q-ary turbo codes with QAM modulations

In this paper a kind of q-ary (q=2/sup t/) turbo codes with the corresponding decoding algorithm are addressed. In addition, a method how to reduce the average number of iterations is discussed. When combined with 16 QAM and 64 QAM modulations, compared with the corresponding binary turbo code, the new coding scheme provides a substantial coding gain on additive white Gaussian noise channels.