Pragmatic trellis coding applied to rectangular QAM

Abstract

Although Ungerboeck's TCM (trellis coded modulation) is attractive in terms of high efficiency with low descending data rate by coding and high coding gain, it is difficult to implement. To remove this complexity, a pragmatic approach to the TCM, which is realized by employing the de facto convolutional code (constraint length K=7 and rate 1/2), was proposed. In this paper, a simpler realization of the TCM of rectangle type 2/sup N/ QAM (N is even number; /spl ges/ 4) by using the pragmatic approach is presented. We have independently shown the convolutional coding and the Viterbi decoding by the decomposition from two-dimensions into each one-dimension. By this decomposition, it is possible to apply the pragmatic approach to minimize the hardware and cost. Therefore, it is very useful for 64 QAM or 256 QAM applications such as digital video broadcasting over digital cable TV (ITU-T J.83) and fixed wireless access (IEEE 802.16) systems. It can be applied not only to single carrier QAM but also to multi-carrier QAM like OFDM.