Multilevel codes for digital HDTV

Multilevel coded modulation is a special case of coded modulation. It was proposed by Imai (1977) at nearly the same time as Ungerboeck (1982) proposed trellis-coded modulation (TCM). A sequence of subsets is coded with a variable rate using block and/or convolutional codes in contrast to TCM based on a rate of m-1/m. We focus on multilevel codes with punctured convolutional codes for digital video broadcasting. In this area the bits normally have different importance. Therefore we use a combination of multilevel codes and multiresolution modulation for unequal error protection.