Noncoherent Ungerboeck-type trellis-coded MPSK

Trellis-coded MPSK proposed by Ungerboeck is noncoherently catastrophic. In this paper, we propose a new scheme in which Ungerboeck-type trellis-coded MPSK is not a noncoherently catastrophic code. In the proposed scheme, a particularly designed differential encoder is added in front of the trellis encoder such that noncoherently-equivalent code sequences correspond to the same data bits. With this differential encoder, trellis-coded MPSK proposed by Ungerboeck is no longer noncoherently catastrophic and thus achieve better error performance. Moreover, new trellis codes which have better bit error rate than Ungerboeckpsilas codes for the proposed scheme are found by computers.