Noncoherently Non-Catastrophic Trellis Coded QAM

In this paper, we propose a new noncoherent trellis-coded QAM (quadrature-amplitude modulation) scheme, in which a differential encoder, a rotator and an inverse signal mapper are added in front of the convolutional encoder. Trellis codes of the proposed scheme are shown to be noncoherently non-catastrophic and have better error performances than conventional trellis-coded QAM. %for short observation length. New trellis codes which, for the proposed cheme, have better bit error rates than Ungerboeck´s codes are found by computer searches.