Research on LDPC - CPM Coded Modulation Communication System

In order to improve the performance of communication system, using integrated coding and modulation process to balance the design, but after trying, we find it difficult to meet the expected requirements, so joint coding modulation came into being. Continuous phase modulation is a kind of constant-envelope modulation schemes with continuous phase which provides good spectral and power efficiency. In this paper, a continuous phase code modulation system based on soft information propagation is proposed. At first, it decodes the CPM by Soft-out Viterbi Algorithm (SOVA), and then uses the soft belief and the hard decision as the input of the LDPC decoder, and finally gets the simulation results. The simulation results show that the method can reach the performance close to the Shannon limit.