Minimal trellises for convolutional codes over rings

The dimensions of the code trellis can be of importance when for example considering the decoding complexity. Forney and Trott (1993) have defined the minimal possible state space of a given convolutional code. Using an algorithm by Vazirani et al. (see IEEE Trans, on Information Theory, vol.42, p.1839-54, 1996), an algorithm that gives the trellis of minimal dimension is presented. The algorithm is easy to use and gives in an straightforward way the minimal dimensions of a code trellis.