Rotational-invariance code design for the system of TCM_CPM

Continuous phase modulation (CPM) is an attractive technique for digital communication, with the development of the trellis coded modulation (TCM), the combination of TCM and CPM is largely applied to improve the performance of MCPM. However, the combination of TCM and CPM cannot utilize unattached differential encoding simply to solve the problem that phase offset caused. As a result, a rotational-invariance system of TCM_CPM is needed to solve the problem. This paper based on the Corneliu Eugen D.Sterian's design of the rotational-invariance TCM_QPSK (QPSK: quad phase shift keying) and TCM_QAM (QAM: quadrature amplitude modulation am), considered the characteristic of CPM, and made a rotational-invariance code design for the system of TCM_CPM, which ensure the system invariant to rotations of the signal constellation by symmetry angles. We did the simulation of rotational-invariance system of 32 states 8CPM and 4CPM TCM_CPM, with pi/4 rotational-invariance.