Multilevel RLL (Runlength Limited) sequences are analyzed. Their noiseless capacity and lower bounds on the channel capacity in the presence of additive white Gaussian noise are given. Moreover, the analytical power spectra formulae for those sequences which generalize the previously derived one for binary sequences are newly derived. We conclude from the analysis of the power spectra that multilevel RLL sequences are attractive from the point of view that they increase information rate while keeping low DC-content and self-clocking capability of binary RLL sequences.

In this paper, coded modulation techniques suitable for satellite broadcasting of digital high-definition TV are studied. An overview of current approaches to satellite broadcasting is presented. New constructions of coded modulation schemes for unequal error protection (UEP), based on both block and trellis codes, are introduced in this paper. The proposed schemes can achieve both better overall performance and enhanced graceful degradation of the received signal, in comparison with existing digital satellite broadcasting approaches.

Geometrically Uniform (GU) codes have been a center of attention because their symmetric properties along with group algebraic structure provide benefits on their design and perfomance evaluation. We have been following a class of GU codes tha we call Strictly Geometrically Uniform (SGU) codes. Our studies had started from devising a way to get SGU trellis codes from Non-SGU (NSGU) constellations. Essentially, SGU multidimensional constellations were derived from an 1- or 2-dimensional NSGU constellations. Some simple good codes were then found, and the novelty is that they rely on symmetries of permutation of channel symbols. Applying the same method to PSK-type constellations, which is SGU, yielded again good codes, along with results regarding their algebraic structure.