Comments on "The Design of Trellis Coded MPSK for Fading Channels: Set Partitioning for Optimum Code Design"

Multiple trellis coded modulation (MTCM) which assigns more than one signal per trellis branch achieves better signal diversity than conventional TCM for the transmission of digital information on a fading channel. The paper above presents a set partitioning method which was claimed to maximize the effective length (L_min) and the minimum product distance (d_pmin). In this paper, it is observed that this set partitioning did not take into account that the MPSK signal sets (M> 4) are nonregular where then the worst case distance corresponding to each signal selector should be considered