Abstract
It is already known that a trellis code T which is constructed by using the encoder of a convolutional code C with short constraint length followed by a delay processor and a signal mapper is equivalent to a trellis code with large constraint length and can achieve a large free distance. In this paper, we show that it is possible to design the signal mapper with another rule rather than the set partitioning criterion used in earlier publications to construct a trellis code with an even larger free distance. Moreover, instead of the multilevel decoding used in earlier publications, we use iterative decoding to efficiently take advantage of this possibly larger free distance. We consider the tail-biting design of T for short packet transmission. Comparisons with the conventional trellis code and the parallel concatenated turbo code are provided.